User manual

ManualsBrandsWACHENDORFF ManualsPanel-Mount InstrumentsMeter 0 -25 k Hz

Sending Serial Commands and Data

When sending commands to the meter, a string containing at least one

command character must be constructed. A command string consists of a

command character, a value identifier, numerical data (if writing data to the

meter) followed by a command terminator character, * or $.

Command Chart

ID Value Description MNEMONIC Transmit Details (T and V)

A Counter A CTA

6 digit positive/5 digit

negative (with minus sign)

B Counter B CTB 5 digit, positive only

C Rate RTE 5 digit, positive only

D Scale Factor A SFA 6 digit, positive only

E Scale Factor B SFB 6 digit, positive only

CLD

SP2

SP1

6 digit positive/5 digit

negative (with minus sign)

per setpoint Assignment,

same as Counter or Rate

per setpoint Assignment,

same as Counter or Rate

T, V, R

T, V

T, V, R

Command String Construction

The command string must be constructed in a specific sequence. The meter

does not respond with an error message to illegal commands. The following

procedure details construction of a command string:

1. The first 2 or 3 characters consist of the Node Address Specifier (N) followed

by a 1 or 2 character node address number. The node address number of the

meter is programmable. If the node address is 0, this command and the node

address itself may be omitted. This is the only command that may be used in

conjunction with other commands.

2. After the optional address specifier, the next character is the command

character.

3. The next character is the register ID. This identifies the register that the

command affects. The P command does not require a register ID character. It

prints all the active selections chosen in the Print Options menu parameter.

4. If constructing a value change command (writing data), the numeric data is

sent next.

5. All command strings must be terminated with the string termination

characters * or $. The meter does not begin processing the command string

until this character is received. See timing diagram figure for differences in

meter response time when using the * and $ terminating characters.

Command String Examples:

1. Node address = 17, Write 350 to the Setpoint 1 value

String: N17VF350*

2. Node address = 5, Read Counter A, response time of 50 msec min

String: N5TA*

3. Node address = 0, Reset Setpoint 1 output

String: RF*

4. Node address = 31, Request a Block Print Output, response time of 2 msec min

String: N31P$

Transmitting Data to the Meter

Numeric data sent to the meter must be limited to transmit details listed in the

must have a minus sign. The meter ignores any decimal point and conforms the

number to the scaled resolution. (For example: The meter’s scaled decimal point

position is set for 0.0 and 25 is written to a register. The value of the register is

now 2.5. In this case, write a value of 250 to equal 25.0).

Note: Since the meter does not issue a reply to value change commands, follow

with a transmit value command for readback verification.

Applicable

Commands

Initiates a block print output. Registers in the

print block are selected in Print Options.

Block Print Request

(read)

Reset a count value or setpoint output. Must

be followed by a register ID character

ResetR

Write to register of the meter. Must be

followed by a register ID character and

numeric data.

Value Change (write)V

Read a register from the meter. Must be

followed by a register ID character.

Transmit Value (read)T

Address a specific meter. Must be followed

by one or two digit node address. Not

required when node address = 0.

Node (meter)

Address Specifier

NotesDescriptionCommand

set to 9600 baud. This is the factory default setting, so a new meter should

arrive ready for copying. The meter sending the program settings (master)

should be set to the desired baud rate for the application (if different than

9600). This baud rate setting will then be copied to the receiver(s).

Copy Connections:

To connect the LD meters for copying, refer to section 3.5 Serial Wiring for

details. The meter shown in the figures as LD METER will be the master.

1. RS232 - Allows copying from the master meter to a single receiver only.

2. RS485 - Allows copying from the master meter to one or more receivers

simultaneously. Up to 31 receiving meters can be connected during copying.

Copy Procedure:

1. Connect the master and receiver(s) using RS232 or RS485 terminals.

2. Apply power to the meters. The receiving meter(s) must be operating in the

normal display mode (not programming mode).

3. On the master meter, proceed to the Copy Program Settings parameter and

select  to begin copying.

4. During the copy process (~ 2 sec.), the master meter displays an upload message

() while the receiver(s) displays a download message (). This

indicates successful communication between the master and receiver(s).

5. When copying is completed, all receivers display the power-up sequence and

return to normal operating mode, programmed with all the same settings as

the master meter. The master remains at the  prompt, ready for another

receiver(s) to be connected for copying.

Setpoint 1

(Reset Output 1)

Setpoint 2

(Reset Output 2)

Counter A Count

Load Value

Receiving Data From The Meter

Data is transmitted from the meter in response to either a transmit command

(T), a block print request command (P) or a User Input print request. The

response from the meter is either a full field transmission or an abbreviated

transmission, depending on the selection chosen in Module 5.

Full Field Transmission

* These characters only appear in the last line of a block print.

The first two characters transmitted are the meter address. If the address

assigned is 0, two spaces are substituted. A space follows the meter address field.

The next three characters are the register mnemonic, as shown in the Register

Identification Chart.

The numeric data is transmitted next. The numeric field (bytes 7 to 18) is 12

characters long. When a requested counter or rate value exceeds the meter’s

display limits, an * (used as an overflow character) replaces a space in byte 7.

Byte 8 is always a space.

The remaining ten positions of this field consist of a minus sign (for negative

values), a floating decimal point (if applicable), and eight positions for the

requested value. The data within bytes 9 to 18 is right-aligned with leading

spaces for any unfilled positions.

The end of the response string is terminated with a <CR> and <LF>. After the

last line of a block print, an extra <SP>, <CR> and <LF> are added to provide

separation between the print blocks.

Byte Description

1, 2 2 byte Node Address field [00-99]

3 <SP> (Space)

4-6 3 byte Register Mnemonic field

7-18

19 <CR> (carriage return)

20 <LF> (line feed)

21 <SP>* (Space)

22 <CR>* (carriage return)

23 <LF>* (line feed)

12 byte data field; 10 for number, one for sign, one for decimal point