Operating instructions Bidirectional Data Interface METTLER TOLEDO AT/MT/UMT Balances
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METTLER TOLEDO AT/MT/UMT Balances Welcome... ...to data communications with the METTLER TOLEDO AT/MT/UMT balance! With this instrument you have purchased a top quality product of weighing technology. One of the goals in developing of the AT/MT/UMT family – outstanding ergonomics – will provide a completely new “feel” for weighing. With computers and robots entering the laboratories, the remote control of instruments is becoming increasingly important.
AT/MT/UMT Balances METTLER TOLEDO Contents Overview ...................................................................................................... 5 Interface Characteristics ............................................................................... Unidirectional Mode ......................................................................................... Bidirectional Mode ......................................................................................... Current Loop Interface ...
METTLER TOLEDO AT/MT/UMT Balances The RS-232 Interface .................................................................................... 75 The ABC of RS-232 ........................................................................................ 75 The RS-232 Connection of the AT/MT/UMT ........................................................ 77 The METTLER TOLEDO CL Interface ................................................................ 78 CL for Programmers .......................................
AT/MT/UMT Balances METTLER TOLEDO 4
METTLER TOLEDO AT/MT/UMT Balances Overview This manual is not intended to be a course in data communications, but rather to provide specific information regarding the interface characteristics of the AT/MT/UMT balances. It is divided into several sections: • • • • • • • • • • • Interface characteristics Transmission modes Commands in alphabetical order Configuration of the interface RS-232 interface METTLER TOLEDO CL interface Interface connectors Data format 7-segment text representation If all fails...
AT/MT/UMT Balances METTLER TOLEDO Interface Characteristics All balances of the AT/MT/UMT series are equipped with a serial interface having the following parameters: • • • • • Asynchronous transmission 1 Start bit 7 Data bits 1 Parity bit (selectable) 1 Stop bit Depending on the application, you may select between unidirectional and bidirectional data transmission and between current and voltage operation. This section briefly describes the various modes.
METTLER TOLEDO AT/MT/UMT Balances Voltage-controlled Interface (RS-232) This popular interface, which is found almost universally in data-processing equipment, is fully supported by the AT/MT/UMT balances. Break The situation where the interface input of the balance is inactive for longer than the duration of a single character (i.e. current interrupted or voltage level positive) is called a break.
AT/MT/UMT Balances METTLER TOLEDO Galvanic Isolation All interface connections of the AT/MT/UMT balance are isolated electrically from the rest of the electronics. This elaborate measure effectively shields the measurement circuits from electrical noise, which could otherwise enter the balance via the attached peripheral devices. Furthermore, there is no way for loop currents, resulting from differing potentials of the system devices (balance, computer), to flow along the data lines.
METTLER TOLEDO AT/MT/UMT Balances Transmission Modes The balance can be set to transmit results in a variety of ways: “Print” (Transfer) Key When the “Print” key is pressed, the balance sends the next stable or the current result, depending on the configuration of the Send parameter (S.Stb, S.ALL, S.Cont, S.Auto). If only stable results are to be transmitted and “doorAuto” is configured in the menu, the draft shield doors close automatically.
AT/MT/UMT Balances METTLER TOLEDO Automatic If the one of the send modes “S.Cont” or “S.Auto” has been configured in the “Interface” sector of the configuration register, data transmission occurs either continuously or automatically after each load change; this is also the case if one of the interface commands “SIR”, “SNR” or “SR” is active. Request by Interface Interface commands such as “S” or “SI” cause the transmission of a single measured value.
METTLER TOLEDO AT/MT/UMT Balances Command Overview Command Naming All commands appear in alphabetical order with the command name clearly emphasized in the upper left corner of the page. This helps in easily locating a specific description. If the command name for a certain feature is unknown, the following tips may be helpful: Commands that prompt the balance to send something begin with an S.
AT/MT/UMT Balances METTLER TOLEDO Command Format Commands consist of one or more characters of the ASCII character set. Non-printable characters are not used (except Control-G which sounds the balance's beeper). No distinction is made between uppercase and lowercase letters, except in commands where this is significant, like in the text argument of the “D text ” command.
METTLER TOLEDO AT/MT/UMT Balances But not: CFparam1 CF param3 CF param1 param2 (no space after command name) (param3 or param4 allowed only after param1 or param2) (either param1 or param2 allowed, but not both) Error Messages If the balance cannot process a command, it reports the reason as follows: ES (Error Syntax) The command is incorrectly built, or it does not exist. Example: U 1.5U2. EL (Error Logical) executed.
AT/MT/UMT Balances METTLER TOLEDO CFG STOP (Configuration Stop). The user has pressed the “Cancel” key, or the “Set” key without changing a parameter, or no key has been pressed for one minute. No change in the configuration has occurred. Note: The command CFG (and also Rn or RK) may be used to inhibit the user from changing the configuration while an application is running.
METTLER TOLEDO AT/MT/UMT Balances An Example The example below shows how the balance can be set up for a particular application through a series of commands. The assignment is to check boxes containing 100 parts weighing 0.25 g each. Overfilling by three parts or underfilling by one part is tolerated. The weight of the box is 21.5 g. The weighing results are to be transmitted automatically. Command Action @ Resets the balance to the power-on state. UX g Ensures that the weight unit is grams.
AT/MT/UMT Balances METTLER TOLEDO 16
METTLER TOLEDO AT/MT/UMT Balances Commands AD ................... AutoDoor ............................................................................................................ B ..................... Base .................................................................................................................. CA ................... Calibration ......................................................................................................... CFD .................
AT/MT/UMT Balances METTLER TOLEDO AD AutoDoor Function: Turns the automatic draft shield operation on or off. Format: AD[ n|?] Description: n is either 0 or 1. AD 0 turns the automatic draft shield operation off. AD 1 turns it on. AD without parameter selects the factory setting.
METTLER TOLEDO AT/MT/UMT Balances B Base Function: Subtracts a constant weight value from all weighing results (tare preset). Format: B[ offset] Description: offset is a positive weight value, expressed in the current weight unit 1. This value is subtracted from all future weighing results. The net weight symbol N identifies the mode in the display. The sum of offset and any tare value must not exceed the maximum load range of the balance.
AT/MT/UMT Balances METTLER TOLEDO CA Calibration Function: Triggers the automatic calibration or calibration test, changes the calibration mode, returns calibration status. Format: CA[ n|U|S|T|?] Description: n is either 0 or 1. CA starts the automatic internal calibration and linearization. CA 0 sets the mode CALIN “Auto off” (the internal calibration is launched by the user or through the CA command). CA 1 sets the mode CALIN “Auto on” (fully automatic calibration).
METTLER TOLEDO AT/MT/UMT Balances CA S sends the current calibration control status as follows: CA=I “Idle”; no automatic calibration pending CA=W “Waiting”; automatic calibration cycle will occur at the next possible opportunity. The AUTOCALIN symbol is lit. CA=CA Automatic calibration is in progress. CA=CX Calibration has been started manually or by command. CA=CT Calibration test is running. This command may be issued even while a calibration cycle is in progress. CA T starts the calibration test.
AT/MT/UMT Balances METTLER TOLEDO CFD Configuration Defaults Function: Sets all balance parameters, except those for the serial interface, to the factory setting. Format: CFD Description: CFD essentially causes resetting of the balance to the standard configuration.
METTLER TOLEDO AT/MT/UMT Balances CFE Store Configuration Function: Saves the current configuration in the permanent memory (EAROM) of the balance. Format: CFE Description: Most settings in the configuration register of the balance as well as the weighing parameters (vibration and weighing process adapters) can be changed with suitable interface commands. The changes are lost, however, when the balance is switched off or an interface break occurs.
AT/MT/UMT Balances METTLER TOLEDO CFG Configuration Access Function: Controls the user’s access to the configuration register. Format: CFG[ n|?] Description: n is either 0 or 1. CFG 0 inhibits the user from accessing the configuration register. CFG 1 allows access to the configuration register, provided the jumper in the program cassette is set to the “unprotected” position. CFG without parameter selects the access mode according to the jumper in the program cassette.
METTLER TOLEDO AT/MT/UMT Balances CFP Configuration Print Function: Prompts the balance to send the contents of the configuration register. Format: CFP Description: After CFP the balance sends the contents of the configuration register as normal text. Note that this information does not necessarily reflect the current configuration since that could have been changed temporarily by interface commands.
AT/MT/UMT Balances METTLER TOLEDO CFR Configuration Read Function: Returns the current balance configuration as a string in the Intel hex format. Format: CFR Description: After this command, the balance transmits its current configuration as a sequence of characters. The string is arranged in Intel hex format, that is, it begins with a colon and ends with a checksum. CFR is usually used in tandem with the CFW (Configuration Write) command.
METTLER TOLEDO AT/MT/UMT Balances CFW Configuration Write Function: Sends a configuration setting in Intel hex format to the balance. Format: CFW config Description: config is a string in the Intel hex format, usually acquired by using the CFR command. This command selects the balance setting that was valid at the time config was determined.
AT/MT/UMT Balances METTLER TOLEDO D Display Text Function: Shows an arbitrary text on the balance display. Format: D[ [text[;[unit][;[symbol]]]]] Description: text is a sequence of printable characters taken from the 7-bit ASCII character set. The text is written into the display left-justified. If text includes more characters than the display can hold, the characters first entered are lost.
METTLER TOLEDO D Zweck: Examples: Format: AT/MT/UMT Balances Display Text Many characters of the ASCII set can be represented only roughly with seven segments. The section “7-Segment Representation of Text” in the Appendices contains a list of the symbols used. Zeigt einen beliebigen Text auf der Waagenanzeige. D HALLO D -23.
AT/MT/UMT Balances METTLER TOLEDO DB Beep Function: Controls the built-in sound generator. Format: DB[ n|C|E] Description: n is a natural number in the range 0 to 3. With this command, the user can be alerted in a variety of ways. DB without parameter generates a short signal. DB 1 generates a long signal. DB 2 produces a double beep. DB 3 triggers a long signal, followed by a short one.
METTLER TOLEDO AT/MT/UMT Balances DST Display Status Function: Controls the behavior of the status indicators for vibration adapter (wave symbol), weighing process adapter (drop symbol) and interface (I/O symbol). Format: DST[ n|A|?] Description: n is either 0 or 1. Depending on the configuration, the status indicators are either permanently on or turned off automatically a few minutes after the balance has been switched on. This behavior can be changed with the DST command.
AT/MT/UMT Balances METTLER TOLEDO DSX Display Select Function: Selects the active display if an auxiliary display is attached. Format: DSX[ n] Description: n is either 0 or 1. If an auxiliary display (e.g. GT53) is attached to the balance, DSX can be used to ensure that only the balance display, only the remote display, or both together are controlled by the balance. DSX 1 activates the balance display. The last result obtained remains “frozen” on the auxiliary display.
METTLER TOLEDO AT/MT/UMT Balances DX DeltaTrac Function: Controls the DeltaTrac display. Format 1: Format 2: DX[ pos1[ pos2|-pos2][ T]] DX T|C Description: pos1 and pos2 are natural numbers in the range 0 to 60. With DX, one or two segments or any continuous range of the Mettler DeltaTrac display may be activated. The segments are numbered in the same manner as the minutes of a clock. DX pos1 activates the segment pos1. DX pos1 pos2 shows two individual segments.
AT/MT/UMT Balances METTLER TOLEDO DY Weigh In Function: Defines target weight and tolerances for checkweighing using the Mettler DeltaTrac. Format 1: Format 2: DY[ target[ tol+[ tol-]][ S]] DYB[ target[ tol+[ tol-]][ S]] Description: target, tol+ and tol- are positive weight values expressed in the current weight unit 1. After receipt of the DY command checkweighings can be performed with the balance as described in the operating instructions of the AT/MT/UMT under “Percent weighing”.
METTLER TOLEDO AT/MT/UMT Balances EC Command Acknowledge Function: Turns the command acknowledge mode on or off. Format: EC[ n|?] Description: n is either 0 or 1. EC 1 turns command acknowledge on. This causes the balance to send the message OK after every command that it has recognized as correct. This signifies that it is ready for a new command. EC 0 or EC without parameter switches back to normal mode (no acknowledge).
AT/MT/UMT Balances METTLER TOLEDO EOL End-of-Line Mode Function: Selects the end-of-line mode. Format: EOL[ mode|?] Description: mode is either CR or CRLF. With this command the end-of-line mode can be chosen. Use of this option is described in the section “End-of-Line”. EOL CR selects the mode “Carriage Return is End-of-Line”. EOL CRLF selects the mode “Carriage Return plus Line Feed is Endof-Line”. EOL without parameter selects the factory setting.
METTLER TOLEDO AT/MT/UMT Balances HS Handshake Mode Function: Selects the handshake mode. Format: HS[ mode|?] Description: mode is one of the modes hard, soft, Pause, CL or off. HS hard selects the mode which uses the handshake lines DTR and CTS. HS soft selects the mode which uses the handshake signals XON and XOFF. HS Pause selects the mode which inserts a pause (1s) after every line sent. HS CL selects the METTLER TOLEDO CL handshake mode. HS off turns any handshake off.
AT/MT/UMT Balances METTLER TOLEDO ID Identification Function: Prompts the balance to transmit an identification text. Format: ID Description: ID is useful in a weighing system if the controlling instrument (computer) needs to know the type and the version of the attached balance. The AT balance sends a three-line (four-line*) identification similar to the following example: STD 10.1.09 TYPE : AT 250 0.00.
METTLER TOLEDO AT/MT/UMT Balances IDX Extended Identification Function: Handles the reading and writing of a user-definable identification string. Format: IDX[ id] Description: id is an identification string consisting of exactly seven characters as follows: cnnnnnn where: c = alphabetic character (a…z or A…Z) n = hexadecimal character (0…9 or A…F) This command allows the user to store an arbitrary string (within the restrictions shown above) in the balance.
AT/MT/UMT Balances METTLER TOLEDO M Mode Reset Function: Sets the vibration adapter (wave symbol), the weighing process adapter (drop symbol), the stability detector (ASD), the AutoZero (AZ), and the readout increment (d) to the factory setting. Format: M Description: With the M command a control unit can easily make sure that the balance is in a known state. It has the same effect as calling the six commands MD, MI, ML, MS, MT and MZ in a row, each without parameters.
METTLER TOLEDO AT/MT/UMT Balances MD Readout Increment Function: Modifies the readout increment. Format 1: Format 2: MD[ step|?] MD[[ F| C] ?] and MD[ F|C[ step]] Description: step is a natural number from the series 1, 2, 5, 10. MD allows the reading and modifying of the readout increment parameter of the configuration register. Format 1: (single range balances) For balances with only one weighing range, format 1 applies. MD step sets the readout increment to the value step.
AT/MT/UMT Balances METTLER TOLEDO MD F step sets the readout increment of the fine range to the value step. MD C step sets the readout increment of the coarse range to the value step. MD F sets the readout increment of the fine range to the factory setting. MD C sets the readout increment of the coarse range to the factory setting.
METTLER TOLEDO AT/MT/UMT Balances MI Vibration Adapter Function: Modifies the vibration adapter (wave symbol). Format: MI[ n|?] Description: n is a natural number in the range 1 to 3. n =1: vibration-free environment (small wave symbol) n =2: normal environment (medium wave symbol) n =3: severe vibrations (large wave symbol) MI n sets the vibration adapter to the value n. MI without parameter selects the factory setting.
AT/MT/UMT Balances METTLER TOLEDO ML Weighing Process Adapter Function: Modifies the weighing process adapter (drop symbol) Format: ML[ n|?] Description: n is a natural number in the range 0 to 3. n =0: n =1: n =2: n =3: no adaption dispensing universal setting absolute weighing ML n sets the weighing process adapter to the value n. ML without parameter selects the factory setting.
METTLER TOLEDO AT/MT/UMT Balances MS ASD Function: Modifies the stability detector (ASD). Format: MS[ n|?] Beschreibung: n is a natural number in the range 0 to 7. MS n sets the stability detector to level n. MS 0 disables the stability detector (position “off”). MS without parameter selects the factory setting.
AT/MT/UMT Balances METTLER TOLEDO MT Transmission Mode Function: Modifies the data transmission mode (“Send Mode”) Format: MT[ mode] Description: mode is either Stb, All, Auto, or Cont. MT Stb selects the mode “Send Stable”. MT All selects the mode “Send All”. MT Auto selects the mode “Send Auto”. MT Cont selects the mode “Send Cont”. MT without parameter selects the factory setting.
METTLER TOLEDO AT/MT/UMT Balances MZ AutoZero Function: Turns AutoZero (AZ) on or off. Format: MZ[ n|?] Description: n is either 0 or 1. MZ 0 turns AutoZero off. MZ 1 turns AutoZero on. MZ without parameter selects the factory setting.
AT/MT/UMT Balances METTLER TOLEDO RG Range Select Function: Selects the weighing range. Format: RG[ C|F|?] Description: With multiple-range balances RG can be used to select the weighing range. RG C selects the coarse range (resolution 0.1 mg) RG F selects the fine range (resolution 0.01 mg) RG without parameter toggles between fine and coarse range, like the front panel key.
METTLER TOLEDO AT/MT/UMT Balances RK Restrict Keyboard Function: Allows disabling or enabling of individual balance frontpanel keys. Format: RK[ bbbbbbbb] Description: Each b represents a single key and can have the value 0 or 1. From left to right the following assignments apply: Re-Zero On/Off Print Menu 0.1/0.01 mg Select 2 Select 1 A “0” in the corresponding position disables the key, a “1” enables it. Re-Zero refers to pressing the «On/Off» key, On/Off refers to lifting this key.
AT/MT/UMT Balances METTLER TOLEDO Rn Remote Function: Allows simultaneous disabling or enabling of all balance front-panel keys. Format: R0|R1 Description: R0 enables the keys except for the door keys if they have been disabled by a WI D command. R1 disables all keys. This command has been kept for compatibility reasons. The RK command serves the same purpose, at the same time offering much more flexibility. The symbol REMOTE is shown on the display as long as the keys are disabled.
METTLER TOLEDO AT/MT/UMT Balances RX Restrict External Switches Function: Allows the individual disabling or enabling of the external switches (connection “Re-zero”) Format: RX[ bbbbbbbb] Description: Each b represents a single switch and can have the value 0 or 1. From left to right the following assignments apply: x x x x x Doors Transfer Tare A 0 in the corresponding position disables the switch, a 1 enables it. The positions marked with x are unassigned and are ignored by the balance.
AT/MT/UMT Balances METTLER TOLEDO S Send Stable Function: Prompts the balance to send a single stable weighing result. Format: S Description: This command causes the balance to send the next stable weighing result. If the balance is already stable when receiving the command, transmission occurs immediately. The data string begins with “S ” , identifying a stable result. An overload condition returns SI+, underload returns SI–. Any existing send command is cancelled by S.
METTLER TOLEDO AT/MT/UMT Balances SI Send Immediate Function: Prompts the balance to send a single weighing result immediately, regardless of the stability status. Format: SI Description: After receipt of this command the balance immediately transmits the next weighing result without waiting for stability. The data string begins with “S ” if the weight value is stable, with “SD” if it is unstable.
AT/MT/UMT Balances METTLER TOLEDO SIR Send Immediate and Repeat Function: Prompts the balance to continuously send weighing results, regardless of the stability status. Format: SIR Description: After receipt of this command the balance sends weighing results continuously (about two and a half results per second) under the same conditions as the SI command. The data strings begin with “S ” in the case of a stable weighing result, with “SD” if the weighing results are unstable.
METTLER TOLEDO AT/MT/UMT Balances SNR Send Next and Repeat Function: Prompts the balance to send the next stable weighing result automatically whenever a load change occurs. Format: SNR Description: After receipt of this command the balance sends the next stable result (immediately if it is already stable) and then another one after every load change of at least 0.01 g. Overload is reported as SI+, underload as SI–. Any existing send command is cancelled by SNR.
AT/MT/UMT Balances METTLER TOLEDO SR Send and Repeat Function: Prompts the balance to send an unstable result whenever a load change occurs and then transmit the next stable weighing result. Format: SR[ threshold] Description: threshold is a positive weight value in the current unit 1.
METTLER TOLEDO AT/MT/UMT Balances T Tare Function: Tares the balance or switches it on again after a power failure. Format: T Description: The T command has the same effect as pressing the tare key. If the weight result is stable or the stability detector is switched off, taring occurs immediately. Otherwise, hyphens are shown in the display and results requested by SI or SIR appear as “SI”. In contrast to manual taring, no TA message is generated.
AT/MT/UMT Balances METTLER TOLEDO U Unit Function: Selects a weight unit or a constant divisor for all weighing results. Format 1: Format 2: U[ unit] U[dec] div[ name] Description: Format 1: unit is one of the weight units of the AT/MT/UMT balance: g mg oz ozt tl GN dwt ct C.M. mo The selected weight unit replaces the previous weight unit 2. Weight unit 1 is not accessible as long as the U command is active.
METTLER TOLEDO AT/MT/UMT Balances This command allows the conversion of the weighing results into any “custom” weight unit. The number of decimal places can be selected with the parameter dec. Omission of dec shows the maximum possible number of places for the current unit 1. Error: EL if div is so small that the display capacity would be exceeded. Example: Parts having an average piece weight of 0.125 oz are to be counted: U oz change unit 1 to ounces U0 .125 divisor = 0.
AT/MT/UMT Balances METTLER TOLEDO US Unit Switch Function: Selects the active weight unit. Format: US[ n|?] Description: n is a natural number, either 1 or 2. With this command one of the two weight units unit 1 or unit 2 can be made current. US n selects the weight unit n. US without parameter switches to the next weight unit (from 1 to 2, from 2 to 1). This is equivalent to pressing the corresponding balance key. US ? sends the current setting as follows: weight unit n active.
METTLER TOLEDO AT/MT/UMT Balances UX Unit Change Extended Function: Redefines the weight units 1 and 2. Format: UX[ [unit1][;unit2]|?] Description: unit1 and unit2 each denote one of the weight units of the AT/MT/UMT balance: g mg oz ozt tl GN dwt ct C.M. mo UX unit1 sets weight unit 1 to unit1. UX unit1;unit2 sets weight unit 1 to unit1 and weight unit 2 to unit2. A space character may be used in place of the semicolon. UX ;unit2 sets weight unit 2 to unit2.
AT/MT/UMT Balances METTLER TOLEDO W Write Output Function: Controls the GM54 Output Module or the LV10 Automatic Feeder. Format 1: Format 2: W[ stat] W stat time stat[ time stat]… Description: Format 1: stat is a natural number in the range 0 to 255. With this command the eight digital outputs of the GM54 Output Module accessory can be switched on and off individually.
METTLER TOLEDO AT/MT/UMT Balances Format 2: stat is a natural number in the range 0 to 255. time is a natural number in the range 1 to 60,000. This command can be used to program a series of status changes of the digital outputs with selectable time intervals. The first and the last argument are always a stat condition. The time intervals between the status changes are expressed in milliseconds, with an actual resolution of about 6 ms.
AT/MT/UMT Balances METTLER TOLEDO WI Windows Function: Controls the motorized draft shield doors. Format: WI[ n|?|D[F|X]|E[F|X]] Description: n is either 0 or 1. With the WI command the doors can be either opened or closed, or their position requested. In addition, the mechanical door switches (on the front-panel or external) can be disabled or enabled. WI 0 opens the doors.
METTLER TOLEDO AT/MT/UMT Balances @ Break Function: Cancels all balance setting changes effected via the interface. Format: @ Description: This command has the same effect as a break on the input data line of the balance. It is particularly suited for systems in which a physical break of the data line is not feasible or not desirable, for example in a remote control installation based on modems, or when a local area network (LAN) is involved.
AT/MT/UMT Balances METTLER TOLEDO ? Help Function: Sends an overview of the interface commands. Format: ?[s] Description: Causes the balance to send a list of the major interface commands. Proper representation requires a video terrminal or computer screen, or a printer capable of printing at least 80 characters per line. ?D ?F ?E or ? shows the command list in German. shows the command list in French. without parameter shows the command list in English.
METTLER TOLEDO AT/MT/UMT Balances . Cancel Function: Aborts a time-consuming command execution. Format: . Description: Some commands take quite some time to execute or are unable to finish because of an unstable environment. Rather than wait for a time-out, these commands may be aborted by the cancel command. Like all commands, it requires a return character termination (possibly followed by a line feed) to execute.
AT/MT/UMT Balances METTLER TOLEDO Repeat Command Zweck: Repeats the last command. Format: | Description: By simply sending a return character (or return followed by line feed, depending on the configuration of the EOL parameter) the last valid command is executed again. This feature is especially useful where only a simple terminal is connected to the balance. Error: EL if no valid command is stored (i.e. immediately after turning the balance on or after an interface break).
METTLER TOLEDO AT/MT/UMT Balances Appendices 69
AT/MT/UMT Balances METTLER TOLEDO Interface Configuration All parameters that control the behavior of the interface can be selected in the fourth sector of the configuration register. The four send modes described below define the behavior of the balance after switching on or after an interface break. The send mode can be overwritten at any time by send commands. Send Stable (“S.Stb”) After the key “Print” or the external transfer key has been pressed, the next stable result is transmitted.
METTLER TOLEDO AT/MT/UMT Balances Send Automatic (“S.Auto”) After every weight change of at least 0.01 g the balance automatically transmits the next stable result. A brief beep sounds at the same time. The “Print” key and the external transfer key have the same effect as in the “Send Stable” mode. The data format is not distinguished from that following an “SNR” command.
AT/MT/UMT Balances METTLER TOLEDO The possible parity settings are: even: The parity bit is selected such that the sum of all 1 bits (data word plus parity) is even. odd: The parity bit is selected such that the sum of all 1 bits (data word plus parity) is odd. off (mark): The parity bit is always set to 1. On receipt it is not tested. For the receiver this data format has the same effect as “no parity, two stop bits”. space: The parity bit is always cleared (0). On receipt it is not tested.
METTLER TOLEDO AT/MT/UMT Balances soft (XON/XOFF): This method requires a simple bidirectional data line; no control lines are necessary. Both balance and peripheral device can stop the incoming data flow at any time by sending the character XOFF (ASCII 19, control-S). The character XON (ASCII 17, control-Q) reenables the communication. Many printers as well as most computers can operate with this method (the IBM PC only after suitable programming).
AT/MT/UMT Balances METTLER TOLEDO End-of-Line (“EOL”) Messages sent by the balance are normally terminated by the character sequence CRLF (Carriage Return and Line Feed). Commands are executed only after receipt of the same sequence. Most computer languages regard the character CR alone as end-of-line, however. This might lead to inconvenient programming caused by the necessity of having to strip the line feed character from the beginning of data strings, for example.
METTLER TOLEDO AT/MT/UMT Balances The RS-232 Interface This section describes the electrical features of the RS-232 interface and provides tips on how to use it. RS-232 is without a doubt one of the most widely used interfaces in the world of data communication. Despite its great popularity, it is also the cause of much trouble and frustration.
AT/MT/UMT Balances METTLER TOLEDO A further reason for confusion lies in the naming conventions of the interface lines. For instance, line 2 is called “Transmitted Data”. But this is only correct when seen from the side of the DTE. A DCE actually receives data on the Transmitted Data line. Handshake lines are a particularly rich source of problems.
METTLER TOLEDO AT/MT/UMT Balances The RS-232 Connection of the AT/MT/UMT The balance is wired as a DCE device. The most common application, namely connecting an RS-232 printer to the balance, should therefore pose no problems. Connection to another DCE device (computer, modem, etc.) requires that the data and handshake lines be crossed. Such cables are sometimes referred to as “null modem” and are available from many sources.
AT/MT/UMT Balances METTLER TOLEDO The METTLER TOLEDO CL Interface This section describes the electrical features of the CL interface. The interface operates with a constant current of 20 mA. It must be supplied by an external current source, one each for the transmitting and receiving loop (see illustration). The best results are obtained when the following technical limits are observed: Voltage compliance of source: 15V (+10%, -0%) Current range: 18...24 mA Rise/fall time: 2...
METTLER TOLEDO AT/MT/UMT Balances CL for Programmers This method has the quite undeserved reputation of being complicated and only suitable for current loop connections. It owes its apparent complexity mainly to the sophisticated procedure used to set up the handshake, and the rigid distinction between text characters, termination characters, and code extensions (ESC sequences). In practice, however, simplifications can usually be applied (e.g.
AT/MT/UMT Balances METTLER TOLEDO Balance-controlled Device Output Transmit the character SYN to the balance to inform it that your device understands the CL handshake. The balance responds by echoing the SYN character, indicating that it is now set up for CL handshake. From now on do not send commands to the balance unless you have received an ACK. Bidirectional Handshake Ideally, your device can recognize the end of the break condition.
METTLER TOLEDO AT/MT/UMT Balances The DATA I/O Connector This connector at the rear of the balance is used for attaching peripheral devices with a serial interface, either for RS-232 or CL operation. Ordering information for suitable plugs and cables can be found in the brochure Technical specifications and accessories.
AT/MT/UMT Balances METTLER TOLEDO IBM-PC/AT and compatibles PC/AT (DTE) Balance (DCE) TxD 3 2 Data In RxD 2 12 Data Out CTS 8 4 Handshake Out GND 5 13 GND RTS 7 DSR 6 DCD 1 DTR 4 3 Handshake In Mini-Mettler (15-pin) DB-9 (male) Appropriate cable: 210493 Apple Macintosh Plus, SE, SE/30 and Macintosh II, IIx, IIcx Mac Plus, SE, II TxD- Balance (DCE) 2 Data In RxD- 3 12 Data Out 4 13 GND GND 5 RxD+ 6 DTR 2 3 Handshake In HSK 1 4 Handshake Out Mini-Mettler (1
METTLER TOLEDO AT/MT/UMT Balances The GT Connector All METTLER TOLEDO GT devices are attached to the AT/MT/UMT balance using this connector. In addition, certain devices of the GM series can be connected by use of the GM/GT adapter (210498) (see brochure Technical specifications and accessories of the AT/MT/UMT balance). The connectors are T-shaped so that several devices can be operated at the same time.
AT/MT/UMT Balances METTLER TOLEDO The Re-Zero Connector Remote control of the functions “Open/close Doors”, “Print/Transfer” and “Tare” without using the serial interface is made possible by this connector. Since signals indicating the status of the doors (open, closed or in-between) are also available, a small laboratory automation system can be set up easily. For such purposes METTLER TOLEDO offers a control cable (210494) with loose ends.
METTLER TOLEDO AT/MT/UMT Balances Data Format Weighing result strings are formatted as follows: 1 2 3 4 5 6 ID 7 8 9 10 11 12 13 14 15 16 17 UNIT DATA 18 19 CR 20 LF where: ID DATA UNIT hatched CR, LF Identification Weighing result Weight unit Space (ASCII 32) Carriage Return, Line Feed The identification ID denotes the type of communication: The first character is a Space if the weighing result has been triggered by the “Print” key or the foot switch.
AT/MT/UMT Balances METTLER TOLEDO The weight unit appears left-justified in the UNIT field. The number of characters used is determined by the length of the unit string, up to four characters. The message is terminated by Carriage Return and Line Feed, immediately following the weight unit. If “EOL cr” has been selected in the configuration register, Line Feed is suppressed. If, for some reasons, the balance cannot transmit a valid result (e.g.
METTLER TOLEDO AT/MT/UMT Balances 7-Segment Representation of Text The “D” command allows the display of any kind of text on the balance, restricted only by its capability to represent characters using only seven segments. The following table shows the 95 printable characters of the ASCII character set (ISO-646) and how they appear on the AT/MT/UMT balance. K '. w õ ú `ê ëè ' [ ] ° . - . ê -é SP ! " # $ % & ' ( ) * • , - .
AT/MT/UMT Balances METTLER TOLEDO What if... Murphy’sLaw states that“ if anything can go wrong, it will go wrong”. This applies particularly to the situation where devices of different manufacturers have to be interconnected. The following tips are meant to help put you on the right track to the solution of your problems more quickly. The messages of the balance are too short/too long and completely unintelligible. The baud rates of balance and peripheral device do not match.
METTLER TOLEDO AT/MT/UMT Balances Many printers have a ready key (labeled “Online”, “Ready”, “Select” or something similar). Pressing this key ensures that the printer is ready to receive. An indicator lamp sometimes helps you verify this mode. The computer recognizes the first weighing result without problem, but subsequent results lead to errors. Most computer languages treat the character Carriage Return (CR) as an end-of-line indication, not the Line Feed (LF) as is standard with Mettler balances.
AT/MT/UMT Balances METTLER TOLEDO The symbol REMOTE is lit and can’t be removed. This symbol appears whenever one or more front-panel keys have been disabled by an interface command. Possible commands are: R1, RK or WI D. Try sending R0 or RK without parameter. If the symbol still appears, the door keys have been inhibited by WI D or WI DF. Send WI E to reenable the door keys. The REMOTE symbol should be off now.
METTLER TOLEDO AT/MT/UMT Balances 1st Aid Kit Finally, a few helpful tips taken from seemingly hopeless real-life situations: 1. Make sure that the physical cable connections are in order. This is very important. The best software can’t help you fix a broken or misconnected wire. The wiring diagrams shown earlier may be useful here. 2. Configure the balance as follows: Send Mode: Baud rate: Parity: Handshake: EOL: Send Continuous (“S.
AT/MT/UMT Balances METTLER TOLEDO 6. The balance now transmits… …nothing anymore: The command SI has been accepted, causing the Send Continuous mode to end. Congratulate yourself and advance to step 7. …ET: Excellent. The connection is in order, only the parity settings are not matched yet. …results as before: The balance has not recognized the command. Change the parity setting of the balance and try again. Set the EOL parameter to CR and send the command without Line Feed.
METTLER TOLEDO AT/MT/UMT Balances Glossary ACK — Short for acknowledge. A control character of the ASCII character set having the value 06 (hexadecimal). It is used in the METTLER TOLEDO CL handshake protocol to tell other device that it may send exactly one line of data. ASCII — American Standard Code for Information Interchange. This ubiquitous standard defines how printable and control characters are encoded into 7 bits.
AT/MT/UMT Balances METTLER TOLEDO Configuration register — A set of menus and menu items on the AT/MT/UMT which allow the user to configure the balance for his particular application. Control character — A character of the ASCII character set which does not print, but may be used to control communication devices. Examples: Carriage Return, ACK, XOFF. CR — Carriage Return. A control character of the ASCII character set (0D hexadecimal).
METTLER TOLEDO AT/MT/UMT Balances Hexadecimal — A number system based on 16 numbers instead of the common 10. This allows the easy expression of 4-bit entities. The numbers used are 0…9, then A for 10, B for 11 and so on up to F for 15. LAN — Local Area Network. A system of several devices (usually more than two) connected via a common cable, capable of talking to each other using a defined set of protocols. Normally not associated with RS-232 setups.
AT/MT/UMT Balances METTLER TOLEDO RS-232 — A standard introduced in 1962 by the EIA (Electronic Industries Association) describing the “Interface Between Data Terminal Equipment and Data Communication Equipment Employing Serial Binary Data Interchange”. It covers the mechanical as well as the electrical characteristics of the interface. The latest revision, EIA-232-D (1986), is closely related to the CCITT V.24 specification.
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