AM16/32B Relay Multiplexer Revision: 1/09 C o p y r i g h t © 1 9 8 7 - 2 0 0 9 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The AM16/32B RELAY MULTIPLEXER is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
AM16/32B Relay Multiplexer Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. Function........................................................................1 1.1 Typical Applications.................................................................................1 1.2 Compatibility ............................................................................................2 2.
AM16/32B Relay Multiplexer Table of Contents 6.6.2 Single-ended Thermocouple Measurement .................................. 33 6.6.3 Differential Thermocouple Measurement .................................... 34 6.7 Mixed Sensor Types............................................................................... 34 6.7.1 Mixed Sensor Example: Soil Moisture Blocks and Thermocouples34 7. General Measurement Considerations ....................38 8. Installation .................................................
Cautionary Notes The AM16/32B is not designed to multiplex power. Its intended function is to switch low level analog signals. Switched currents in excess of 30 mA will degrade the relay contacts involved, rendering that channel unsuitable for further low level analog measurement. Customers who need to switch power are directed to Campbell Scientific’s SDM-CD16AC, A6REL-12, or A21REL-12 relays.
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AM16/32B Relay Analog Multiplexer 1. Function The primary function of the AM16/32B Multiplexer is to increase the number of sensors that can be measured by a CR1000, CR3000, CR800, CR850, CR23X, CR10(X), 21X, or CR7 datalogger. The AM16/32B is positioned between the sensors and the datalogger. The AM16/32B is a replacement for CSI’s AM16/32 model. The hardware is the same as the AM16/32A model. The AM16/32B adds a mode to address an individual relay.
AM16/32B Relay Analog Multiplexer NOTE For a discussion of single-ended versus differential analog measurements, please consult the Measurement section of your datalogger manual. As purchased, the AM16/32B is intended for use in indoor, non-condensing environments. An enclosure is required for field or high humidity use. In applications where one or two multiplexers are deployed, the ENC 10/12 (10” x 12”) enclosure is recommended. 1.
AM16/32B Relay Analog Multiplexer FIGURE 1. AM16/32B Relay Multiplexer 3. AM16/32B Specifications Power*: Unregulated 12 VDC Minimum Operating Voltage: from –55C to +40C = 11.3 VDC; from +40C to +85C = 11.8 VDC (See Figure 2 for relay actuation times vs. temperature and supply voltage.) Current Drain: Quiescent: < 210 uA Active: 6 mA typical in “2 x 32” mode 11 mA typical in “4 x 16” mode Reset*: A continuous signal between 3.
AM16/32B Relay Analog Multiplexer Weight: 1.5 lbs. (approx.), 693 g. Mounting Tab Hole Spacing: Expandability** (nominal): 1 inch x 3 inches x 9 inches. Up to 1/8 inch or 3 mm diameter screws (see Figure 22). Maximum Cable Length: Depends on sensor and scan rate. In general, longer lead lengths necessitate longer measurement delays. Refer to datalogger manual for details.
AM16/32B Relay Analog Multiplexer 10.0 8.0 6.0 4.0 16 17.3 15.6 16.9 15.2 16.5 14.8 16.1 14 15.3 14.4 15.7 13.6 14.9 13.2 14.5 12.8 14.1 12 13.3 12.4 13.7 11.6 12.9 11.2 12.5 12.1 10.8 11.3 10 0.0 11.7 10.4 2.0 10.9 9.6 RELAY ACTUATION TIME (ms) 12.0 POWER SUPPLY VOLTAGE 65C 50C 25C -25C FIGURE 2. AM16/32B Relay Actuation Time vs. Temperature and Battery Voltage 4. Operation Subsection 4.1 discusses the terminals that control operation of the multiplexer.
AM16/32B Relay Analog Multiplexer 12V GND CLK RES MUXPOWER CABLE SHIELD N O CR800, CR850 CR10X, CR3000, CR1000 G G 12 V CR23X, CR5000 21X CR7 12 V 12 V +12 V 12 V G G G C1-C4 C1-C8 C1-C8 EXCIT 1-4 EXCITATION C1-C4 C1-C8 C1-C8 C1-C8 725 Card Control FIGURE 3. AM16/32B to Datalogger Power/Control Hookup using CABLE4CBL or MUXPOWER Cable With the 21X or CR7 the AM16/32B connects to the 12 VDC and “ ” terminals for power.
AM16/32B Relay Analog Multiplexer multiple sensor types are connected to the AM16/32B, Mode B allows one sensor type to be measured more frequently than the other sensor types. A more detailed description of Mode B is provided in section 4.2.1.2. The AM16/32B detects a certain sequence on the RESET and CLK inputs to determine if it should operate in Mode A or Mode B; it does this every time the RESET line goes from LO to HI. 4.1.2.
AM16/32B Relay Analog Multiplexer 5 ms (±1 ms) (0 -–100m 75 ms) mss the (0 s) Note: No te:ifif>>125 100m th e B B Address Add ress mode m ode is Aborted. mss Abo rted. Also, Also, Abort Abortcan canhappen happ enifif>>125 100m time tim ebetween b etw eenClk’s.
AM16/32B Relay Analog Multiplexer ' ***** ' "Jump" AM16/32B directly to Channel 6 Scan (100,mSec,0,1) PortSet(5,1) ' Raise Reset line Delay (0,5,mSec) ' Keep reset HI for 5 ms PortSet(5,0) ' Reset line set LO (enters "B Addressing" mode) Delay (0,3,mSec) For i = 1 To 6 ' Pulse CLK line 6 times - addresses Channel 6 PortSet(6,1) ' Raise CLK Delay (0,10,mSec) PortSet(6,0) ' Drop CLK Delay (0,10,mSec) Next i Delay (0,5,mSec) PortSet(5,1) ' Raise Reset - selects Channel 6 (relays make contact) NextScan 4.1.
AM16/32B Relay Analog Multiplexer on average system current drains (e.g. logger, multiplexer, other peripherals and sensors) at the expected ambient temperatures. The average power required to operate an AM16/32B depends on the percentage of time it is active per time period. For example, if a CR10X makes differential measurements on 32 thermocouples every minute, the average current drain due to the AM16/32B would be about ((.030 Sec/chan x 32 chan)/60 Sec) x 6 mA = 0.1 mA.
AM16/32B Relay Analog Multiplexer 4.2.1 COM Terminals A CABLE3CBL, CABLE4CBL, MUXSIGNAL, or CABLE5CBL cable is used to connect the datalogger to the COM terminals. The CABLE3CBL is recommended when the AM16/32B is used in the 4x16 mode. Either the CABLE4CBL or MUXSIGNAL is typically used for the 4x16 mode. The CABLE5CBL is recommended for the 4x16 mode when it is desirable to connect both shields.
AM16/32B Relay Analog Multiplexer four in turn is switched into contact with the four COM terminals. For example, when the first clock pulse is received from the datalogger, SET 1 (1H, 1L, 2H, 2L) are connected with COM (ODD H, ODD L, EVEN H, EVEN L) terminals respectively. When the second clock pulse is received, the first SET is switched out (channel 1 sensor inputs become open circuits) and SET 2 (3H, 3L, 4H, 4L) are connected to the four COM terminals.
AM16/32B Relay Analog Multiplexer FIGURE 7. SCWIN (Short Cut for Windows Program Builder) 5.1 CRBasic Programming The CR5000, CR800, CR850, CR3000, and CR1000 are programmed with CRBasic; for details see the datalogger manual. While the instructions look different than those used to program the older CR10X, CR23X, etc., they perform similar functions. One difference that needs to be pointed out is that with CRBasic measurement results are stored in a variable array, not numbered input locations.
AM16/32B Relay Analog Multiplexer Delay (0,20,mSec) Portset (2,0) ‘Set port 2 low INCREMENT INDEX AND MEASURE I=I+1 'User specified measurement instruction ‘Storing results in Variable(I) END MEASUREMENT LOOP NextSubScan DEACTIVATE MULTIPLEXER Portset (1 ,0) 'Set C1 Low to disable Multiplexer In addition to precision voltage excitation, the CR5000 and CR3000 have programmable current excitation. Current excitation allows a resistance measurement on a four-wire sensor (e.g.
AM16/32B Relay Analog Multiplexer Wiring for CR1000 Program Example AM16/32B (4x16) CS616* Control/Common Sensor Terminals C4 RES Odd H CS616#1_Green C5 CLK Odd L CS616#2_Green 12 V 12 V Gnd #1,2,3_Blk & Clear Gnd Gnd Even H CS616#3_Green 1H COM Odd H Even L #1,2,3_Orange 1L COM Odd L Gnd Gnd 2H COM Even H C6 COM Even L *Three sensors to each set of AM16/32B terminals.
AM16/32B Relay Analog Multiplexer ‘Main Program BeginProg Scan (5,Sec,0,0) ‘scan instructions every 5 sec Battery (Batt_volt) PanelTemp (Panel_temp,250) ‘ ‘Set flag 1 High every 30 min (Note: User can manually set flag 1 high/low) If IfTime (0,30,min)Then flag (1)=high ‘++++++++++++++++++++++++ If Flag(1)=high Then ‘measure 48ea CS616 probes on AM16/32B in (4x16) mode PortSet (4,1) ‘Set Mux Reset line High ‘ I=1 ‘set sub scan loop counter SubScan (0,mSec,16) PulsePort (5,10000) ‘Clock Mux CS616 (Period(I),
AM16/32B Relay Analog Multiplexer 'CR5000 Example Program to measure 16 100 ohm Platinum Resistance Thermometers ‘connected to an AM16/32B multiplexer used in the 4x16 configuration. The program also ‘measures 6 copper constantan 'thermocouples. 'The Thermocouples are connected to differential channels 1-6.
AM16/32B Relay Analog Multiplexer TABLE 1.
AM16/32B Relay Analog Multiplexer Example: 2 sensors per SET, 6 sensors total; two reps specified in measurement instruction; two measurement values assigned to indexed input locations (--); P90 step of 2. Loop count of three.
AM16/32B Relay Analog Multiplexer NOTE If more than the datalogger’s default number of input locations are required, then additional input locations must be assigned using the datalogger *A mode. Consult your datalogger manual for details. #6 Optional Processing - Additional processing is sometimes required to convert the reading to the desired units. It may be more efficient if this processing is done outside the measurement loop. A second loop can be used for processing, if necessary.
AM16/32B Relay Analog Multiplexer GENERALIZED “4x16” MODE PROGRAM LOOPS FOR THE CR23X, CR10(X), 21X, and CR7 21X SAMPLE PROGRAM CR7 SAMPLE PROGRAM CR10X, CR23X SAMPLE PGM * * * 1 01: 60 Table 1 Programs Sec. Execution Interval 1 01: 60 Table 1 Programs Sec. Execution Interval :ACTIVATE MULTIPLEXER 1: Set Port (P20) 1: 1 Set high 2: 1 Port Number ;ACTIVATE MULTIPLEXER 1: Set Port (P20) 1: 1 Set high 2: 1 EX Card 3: 1 Port No.
AM16/32B Relay Analog Multiplexer EXAMPLE “2x32” MODE PROGRAMS - GENERALIZED PROGRAM LOOPS FOR THE CR23X, 21X, CR10(X), AND CR7. 21X SAMPLE PROGRAM * 1 Table 1 Programs 01: 60 Sec. Execution Interval CR7 SAMPLE PROGRAM * 1 Table 1 Programs 01: 60 Sec. Execution Interval ;ACTIVATE MULTIPLEXER 1: Set Port (P20) 1: 1 Set high 2: 1 Port Number ;ACTIVATE MULTIPLEXER 1: Set Port (P20) 1: 1 Set high 2: 1 EX Card 3: 1 Port No.
AM16/32B Relay Analog Multiplexer AM16/32B MODE AM16/32IN IN "4X16" "4X16" MODE CR23X MUX POWER SHIELD GND SETS 1-10 12V H1 G GND L1 C1 RES H2 C2 CLK L2 12V SETS 11-16 EX 1 COM H1 H1 SE 1 COM L1 L1 SE 2 COM H2 H2 COM L2 L2 MUXSIGNAL SHIELD COM COM FIGURE 10.
AM16/32B Relay Analog Multiplexer *1 Table 1 Programs 1: 60 Sec. Execution Interval ;ACTIVATES MULTIPLEXER 1: Do (P86) 1: 41 Set high Port 1 ;BEGINS STRAIN GAGE MEASUREMENT LOOP 2: Beginning of Loop (P87) 1: 0 Delay 2: 10 Loop Count ;CLOCK PULSE 3: Do (P86) 1: 72 Pulse Port 2 ;DELAY 4: Excitation with Delay (P22) 1: 1 EX Chan 2: 0 Delay w/EX (units=.01sec) 3: 1 Delay after EX (units=.
AM16/32B Relay Analog Multiplexer ;POT. MEASUREMENT INSTRUCTION 11: Excite,Delay,Volt(SE) (P4) 1: 2 Reps 2: 5 5000 mV slow Range 3: 1 IN Chan 4: 2 Excite all reps w/EXchan 2 5: 1 Delay (units .01sec) 6: 5000 mV Excitation 7: 11-Loc [:POT #1 ] 8: 1 Mult 9: 0 Offset ;END POT.
AM16/32B Relay Analog Multiplexer that only sensor shield (drain) wires be connected to AM16/32B shield terminals labeled (“ ”). 6.1 Single-Ended Analog Measurement without Sensor Excitation Sensor to AM16/32B wiring - one single-ended sensor not requiring excitation can be connected to an input SET with panel mode switch set to “2x32”. Multiplexer to Datalogger wiring - The COM signal line is input to a single-ended analog input channel.
AM16/32B Relay Analog Multiplexer 6.2 Differential Analog Measurement without Sensor Excitation Sensor to Multiplexer wiring - Up to two differential sensors that don't require excitation may be connected to one input SET with panel switch set to “4x16” mode. Sensor shields are connected to the input “ ” terminals. Multiplexer to Datalogger wiring - The two pairs of COM terminals (ODD H, ODD L and EVEN H, EVEN L) are connected to two pairs of differential analog inputs at the datalogger.
AM16/32B Relay Analog Multiplexer CR23X/ CR800/ CR850/ CR1000 21X/ CR7 CR10(X) CR3000/ CR5000/ EX E E VX H H H L L H H "4 X 16" Mode 0 COM H (ODD) ODD H H COM L ODD L L L COM H (EVEN) EVEN H H H COM L EVEN L AG CABLE5CBL MUXSIGNAL G SHIELD COM SHIELD SENSOR SHIELDS FIGURE 13.
AM16/32B Relay Analog Multiplexer Multiplexer to Datalogger wiring - Signal lines from two COM terminals are connected to two consecutive single-ended analog input channels. One COM terminal is connected to a datalogger switched excitation channel, and the remaining COM line connects to datalogger ground. Up to 32 potentiometers may be measured by two single-ended datalogger channels. 6.3.3 Four Wire Half Bridge (Measured Excitation Current) Sensor to Multiplexer Wiring - one sensor per input SET.
AM16/32B Relay Analog Multiplexer CR23X/ CR800/ CR850/ CR1000 21X/ CR7 CR10(X) CR3000/ / CR5000 0 EX E E VX AG "4 X 16" Mode COM H (ODD) ODD H COM L ODD L H H H H COM H (EVEN) EVEN H L L L L COM L EVEN L G COM SHIELD SENSOR SHIELDS FIGURE 16. Full Bridge Measurement 6.4 Full Bridge Measurements Sensor to Multiplexer wiring – With panel switch set to “4x16” mode, excitation, ground, and the two signal leads may be connected to one input SET (Figure 16).
AM16/32B Relay Analog Multiplexer CR23X/ CR800/ CR850/ CR1000 21X/ CR7 CR10(X) CR3000/ / CR5000 0 AG EX E E VX "4 X 16" Mode COM H (ODD) ODD H COM L ODD L "4 X 16" Mode H H H H COM H (ODD) ODD H L L L L COM L ODD L H H H H COM H (EVEN) EVEN H L L L L COM L EVEN L G COM SENSOR SHIELDS FIGURE 17. Full Bridge Measurement with Excitation Compensation 6.
AM16/32B Relay Analog Multiplexer Two problems would arise due to the properties of thermocouple wire: An extraneous thermocouple voltage would be added to the nonthermocouple signal at the junction of dissimilar metals (e.g. the multiplexer COM terminals). The magnitude of this signal would vary with the temperature difference between the datalogger and the AM16/32B. Some thermocouple wires have a greater resistance than copper, which adds resistance to the non-thermocouple sensor circuit.
AM16/32B Relay Analog Multiplexer If a mix of TCs and other sensor types are multiplexed through the AM16/32B, it is generally best to locate the reference junction on the AM16/32B, as shown in Figure 19. AM16/32B Reference - An external reference, usually a thermistor, can be located at the AM16/32B, as shown in Figure 19. This approach requires an additional single-ended datalogger input to measure the reference.
AM16/32B Relay Analog Multiplexer Exposed ends of thermocouples measuring soil temperature should be electrically insulated to prevent differences in ground potential among the thermocouples from causing errors in the measured temperatures. AM16/32B panel switch set to “4x16” mode. Sensor to Multiplexer wiring - up to three thermocouples per SET; the high side of each thermocouple is input into terminals ODD H, ODD L, and EVEN H.
AM16/32B Relay Analog Multiplexer CR10X Example Program – Thermocouple and Soil Block Measurement AM16/32B AM16/32 CR10(X) G MUXPOWER SHIELD GND 12V 12V G GND C1 RES C2 CLK 1H COM COM 1L SETS 1-16 ODD H ODD L ODD H ODD L EX 1 107 2L SETS 1-16 AG 1K 0.1% EX 2 COM EVEN H EVEN H COM EVEN L EVEN L 2H AG G MUXSIGNAL SHIELD COM FIGURE 21. Thermocouple and Soil Block Measurement for CR10X Example 33 LOCATIONS ALLOCATED TO INPUT STORAGE) *1 1: 60 Table 1 Programs Sec.
AM16/32B Relay Analog Multiplexer CLOCK PULSE 4: Do (P86) 1: 72 Pulse Port 2 5: Excitation with Delay (P22) 1: 1 EX Chan 2: 2 Delay w/EX (units=.01 sec) 3: 0 Delay after EX (units=.01 sec) 4: 1 mV Excitation 5: 0 MEASURES 1 THERMOCOUPLE PER LOOP 6: Thermocouple Temp (DIFF) (P14) 1: 1 Rep 2: 1 2.
AM16/32B Relay Analog Multiplexer 9:TC #8 27:SOIL M#10 10:TC #9 28:SOIL M#11 11:TC #10 29:SOIL M#12 12:TC #11 30:SOIL M#13 13:TC #12 31:SOIL M#14 14:TC #13 32:SOIL M#15 15:TC #14 33:SOIL M#16 16:TC #15 34:_________ 17:TC #16 35:_________ 18:SOIL M #1 36:_________ CR1000 Example Program – Thermocouple and Soil Block Measurement 'CR1000 Series Datalogger 'Declare Public Variables Public PTemp, batt_volt, TCTemp(16), Soil(16) Dim I 'Counter for setting Array element 'Define Data Tables DataTable (Avg15Min,
AM16/32B Relay Analog Multiplexer 'Deactivate Multiplexer PortSet (1 ,0) 'Call Data Table CallTable Avg15Min Next Scan EndProg 7. General Measurement Considerations Long lead lengths – Longer sensor-to-AM16/32B leads result in greater induced and capacitively coupled voltages (cross-talk) between cable wires. To minimize capacitive effects CSI recommends the use of cabling having Teflon, polyethylene, or polypropylene insulation around individual conductors.
AM16/32B Relay Analog Multiplexer plate with 1-inch hole grid suitable for mounting the AM16/32B. The enclosures have a cable bushing to accommodate the sensor lines. These standard enclosures are rain-tight, but not water-proof. The enclosure lids are gasketed. The screws on the outside of the enclosure should be tightened to form a restrictive seal. In high humidity environments, user supplied foam, putty, or similar material helps to reduce the passage of moisture into the enclosure via cable conduits.
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Appendix A. AM16/32B Improvements The AM16/32B replaced the AM16/32A in January 2008. A clocking mode was added that uses a relay address to go directly to a specific channel. This reduces power consumption and wear on the relay switches. The AM16/32A replaced the AM16/32 in October 2006. The AM16/32A’s improvements over the AM16/32 are better ESD and surge protection, a main ground lug, and a newer processor.
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