INSTRUCTION MANUAL AM16/32 Relay Multiplexer Revision: 9/04 C o p y r i g h t ( c ) 1 9 8 7 - 2 0 0 4 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 AM16/32 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.
AM16/32 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.
AM16/32 Relay Multiplexer Table of Contents 6.6 Thermocouple Measurement.................................................................. 28 6.6.1 Measurement Considerations ....................................................... 28 6.6.2 Single-ended Thermocouple Measurement .................................. 30 6.6.3 Differential Thermocouple Measurement..................................... 31 6.7 Mixed Sensor Types............................................................................... 31 6.7.
Cautionary Notes The AM16/32 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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AM16/32 Relay Analog Multiplexer 1. Function The primary function of the AM16/32 Multiplexer is to increase the number of sensors that can be measured by a CR1000, CR23X, CR10(X), 21X, or CR7 datalogger. The AM16/32 is positioned between the sensors and the datalogger. The AM16/32 is a replacement for CSI’s AM416 and AM32 models. Mechanical relays in the AM16/32 connect each of the sensor channels in turn to a common output destined for the datalogger.
AM16/32 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 AM16/32 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 AM-ENC (10” X 12”) enclosure is recommended. 1.
AM16/32 Relay Analog Multiplexer FIGURE 1. AM16/32 Relay Multiplexer 3. AM16/32 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.
AM16/32 Relay Analog Multiplexer Dimensions: Length – 23.9 cm (9.4") Width - 10.2 cm (4.0") Depth - 4.6 cm (1.8") Weight: 1.5 lbs. (approx.), 693 g. With AM ENC enclosure: 10.0 lbs., 4.54 kg (approx.) 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 21). Maximum Cable Length: Depends on sensor and scan rate. In general, longer lead lengths necessitate longer measurement delays.
AM16/32 Relay Analog Multiplexer RELAY ACTUATION TIME (ms) 12.0 10.0 8.0 6.0 4.0 2.0 16 15.6 15.2 14.8 14 14.4 13.6 13.2 12.8 12 12.4 11.6 11.2 10.8 10 10.4 9.6 0.0 POWER SUPPLY VOLTAGE 65C 50C 25C -25C FIGURE 2. AM16/32 Relay Actuation Time vs. Temperature and Battery Voltage. 4. Operation Subsection 4.1 discusses the terminals that control operation of the multiplexer. These terminals are located at the left-hand side of the multiplexer as shown in Figure 1. Subsection 4.
AM16/32 Relay Analog Multiplexer CR10X 12V GND CLK RES MUXPOWER SHIELD CR23X G CR1000 CR5000 21X CR7 +12 V 12 V G 12 V 12 V 12 V 12 V G G G G C1-C8 C1-C8 C1-C8 C1-C8 EXCIT 1-4 EXCITATION C1-C8 C1-C8 C1-C8 C1-C8 C1-C8 725 Card Control N O FIGURE 3. AM16/32 to Datalogger Power/Control Hookup With the 21X or CR7 the AM16/32 connects to the 12VDC and “ ” terminals for power.
AM16/32 Relay Analog Multiplexer With the 21X and CR7 dataloggers, switched excitation is generally used to clock the multiplexer (Instruction 22 configured for 5000 mV excitation). If no switched excitation channel is available, it is possible to clock using control ports. See Section 5.1 for details. In the case of the CR5000, CR1000, CR23X, and CR10(X), a control port is generally used to clock the multiplexer.
AM16/32 Relay Analog Multiplexer The average power required to operate an AM16/32 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 AM16/32 would be about ((.030 Sec/chan x 32 chan)/60 Sec) x 6 mA = 0.1 mA. Under the same conditions, a 2 second execution interval rate increases the average system current drain to about ((.030 Sec/chan x 32 chan)/2 Sec) x 6 mA = 2.
AM16/32 Relay Analog Multiplexer 4.2.1 COM Terminals The four terminals dedicated to multiplexer-datalogger connection are located under the blue “COM” next to the mode switch. The terminals are labeled: ODD H, ODD L, EVEN H, and EVEN L. In “4X16” mode the AM16/32 maintains the four “COM” terminals electrically isolated from one another. In “2X32” mode the AM16/32 maintains an internal connection between ODD H and EVEN H and between ODD L and EVEN L.
AM16/32 Relay Analog Multiplexer With panel switch set to “2X32” mode the white channel numbers apply. The SETs are labeled beginning with 1H, 1L and ending with 32H, 32L. In “2X32” mode when the AM16/32 selects a given channel the “H” sensor terminal is relay connected to both COM “H” terminals and the “L” sensor terminal is connected to both COM “L” terminals (COM ODD H connects to COM EVEN H and COM ODD L connects to COM EVEN L when panel switch is in “2X32” mode). 5.
AM16/32 Relay Analog Multiplexer When a number of similar sensors are multiplexed and measured, the Instructions to clock the AM16/32 and to measure the sensors are placed within a program loop. For the CR23X, CR10(X), 21X, and CR7 the generalized structure of a program loop is as follows: TABLE 2.
AM16/32 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.
AM16/32 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.
AM16/32 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 01: P20 Set Port 01: 1 Set high 02: 1 Port Number ACTIVATE MULTIPLEXER 01: P20 Set Port 01: 1 Set high 02: 1 EX Card 03: 1 Port No.
AM16/32 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 01: P20 Set Port 01: 1 Set high 02: 1 Port Number ACTIVATE MULTIPLEXER 01: P20 Set Port 01: 1 Set high 02: 1 EX Card 03: 1 Port No.
AM16/32 Relay Analog Multiplexer CR23X AM16/32 IN "4X16" MODE 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 FIGURE 9. Wiring Diagram for Strain Gages and Potentiometers #8 Additional Loops - Additional loops may be used if sensors that require different measurement instructions are connected to the same multiplexer.
AM16/32 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=.
AM16/32 Relay Analog Multiplexer DELAY 10: Excitation with Delay (P22) 1: 1 EX Chan 2: 0 Delay w/EX (units=.01sec) 3: 1 Delay after EX (units=.01sec) 4: 0 mV Excitation 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.
AM16/32 Relay Analog Multiplexer GENERALIZED CR5000/CR1000 PROGRAMMING SEQUENCE: ACTIVATE MULTIPLEXER/RESET INDEX Portset (1 ,1) 'Set C1 high to Enable Multiplexer I=0 BEGIN MEASUREMENT LOOP SubScan(0,sec,16) CLOCK PULSE AND DELAY Portset (2,1 ) ‘Set port 2 high 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
AM16/32 Relay Analog Multiplexer 'CR5000 Example Program to measure 16 100 ohm Platinum Resistance Thermometers ‘connected to an AM16/32 multiplexer used in the 4x16 configuration. The program also ‘measures 6 copper constantan 'thermocouples. 'The Thermocouples are connected to differential channels 1-6.
AM16/32 Relay Analog Multiplexer Wiring for CR1000 Program Example AM16/32 (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 AM16/32 terminals.
AM16/32 Relay Analog Multiplexer I-1 ‘set sub scan loop counter SubScan (0,mSec,16) PulsePort (5,10000) ‘Clock Mux CS616 (Period(I),3,1,6,3,1.0,0)‘measure 3ea CS616 probes I=I+3 NextSubScan ‘ For I=1 to 48 ‘convert CS616 period to Volumetric Water Content VWC(I)=a0 + a1*Period(I) + a2*Period(I)^2 Next ‘ PortSet (4,0) ‘Set Mux Reset line Low flag(1)= low EndIf ‘+++++++++++++++++++++++++++ ‘ CallTable Dat30min ‘Call Output Tables NextScan EndProg 5.
AM16/32 Relay Analog Multiplexer Low level single-ended measurements are not recommended in 21X applications where the 21X's internal 12VDC supply is used to power the multiplexer or other peripherals (see Section 4.1.4). NOTE 21X 21x CR7 CR7 H CR23X/ CR10(X) CR10(X) CR1000/CR5000 CR23X/CR5000 H "2 X 32" Mode H AG MUXSIGNAL G SHIELD COM ODD H ODD H (+) SENSOR COM ODD L ODD L (-) SENSOR SHIELD COM AM16/32 FIGURE 10.
AM16/32 Relay Analog Multiplexer 6.3 Half Bridge Measurements Measurements of this type may be subdivided into three categories based on completion resistance and the presence or absence of measured excitation. If the sensor's completion resistor(s) are installed at the datalogger panel (example: a CSI 107 probe modified for multiplexer use), then three probes per SET may be excited and measured in “4X16” mode (Figure 12). However, if the circuit is completed within the sensor (e.g.
AM16/32 Relay Analog Multiplexer CR23X/ 21X CR1000/ CR23X/ 21x CR7 CR7 CR10(X) CR10(X) CR5000 CR5000 E E E/VX H H L L "4 X 16" Mode COM H (ODD) ODD H H COM L ODD L L COM H (EVEN) EVEN H COM L EVEN L AG G MUXSIGNAL SHIELD COM SHIELD SENSOR SHIELDS FIGURE 13. Potentiometer Hook-up and Measurement 6.3.2 Potentiometer Measurement Sensor to Multiplexer wiring – if panel switch is set to ”4X16” mode, up to two potentiometers may be connected to one input SET.
AM16/32 Relay Analog Multiplexer 21X 21x CR7 CR7 CR23X/ CR1000/ CR23X/ CR10(X) CR5000 "4 X 16" Mode CR10(X) CR5000 E E E/VX H H L L COM H (ODD) ODD H H COM L ODD L L COM H (EVEN) EVEN H COM L EVEN L AG H H H L L L G COM SHIELD SENSOR SHIELDS FIGURE 14. Four Wire Half Bridge Hook-up and Measurement The CR5000 also has current excitation channels which allow a resistance measurement.
AM16/32 Relay Analog Multiplexer A problem with making full bridge measurements with this configuration is that the resistance of the lead wire and multiplexer relays can cause a voltage drop, reducing the excitation at the bridge. The following section describes a configuration that compensates for this by measuring the excitation at the bridge. 6.
AM16/32 Relay Analog Multiplexer 6.6 Thermocouple Measurement The datalogger manuals contain thorough discussions of thermocouple measurement and error analysis. These topics will not be covered here. 6.6.1 Measurement Considerations Reference Junction - As shown in Figure 17 and 18, two reference junction configurations are possible: 1) reference located at the datalogger or 2) reference at the AM16/32.
AM16/32 Relay Analog Multiplexer 21x CR7 21X CR7 CR23X/ CR23X/ CR10(X) CR1000/ CR5000 CR10(X) CR5000 H H H L L L H H H L L L "4 X 16" Mode CU CO CU CO COM ODD H ODD H COM ODD L ODD L COM EVEN H EVEN H COM EVEN L EVEN L CO CU CO SENSOR SHIELDS COM G CU FIGURE 17. Differential Thermocouple Measurement with Reference Junction at the Datalogger.
AM16/32 Relay Analog Multiplexer result in an approximate one degree measurement error. Installing the aluminum cover plate (included with AM16/32) helps to minimize gradients. For best results the AM16/32 should be shielded and insulated from all radiant and conducted thermal sources. When an enclosure is used, gradients resulting from heat conducted along the thermocouple wire can be minimized by coiling some wire inside the enclosure.
AM16/32 Relay Analog Multiplexer same composition as the high side of the thermocouples. Also, the wire that connects COM EVEN L to datalogger ground should be of the same composition as the low side of the thermocouples. If the reference junction is at the AM16/32 (CSI 107 thermistor, RTD, etc.), then copper wire should be used to connect COM terminals to the datalogger. 6.6.3 Differential Thermocouple Measurement AM16/32 panel switch set to “4X16” mode.
AM16/32 Relay Analog Multiplexer 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 20. Thermocouple and Soil Block Measurement EXAMPLE PROGRAM - THERMOCOUPLE AND SOIL BLOCK MEASUREMENT (PROGRAM IS FOR CR10(X) - 33 LOCATIONS ALLOCATED TO INPUT STORAGE) *1 1: 60 Table 1 Programs Sec.
AM16/32 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.
AM16/32 Relay Analog Multiplexer 6:TC #5 24:SOIL M #7 7:TC #6 25:SOIL M #8 8:TC #7 26:SOIL M #9 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:_________ 7. General Measurement Considerations Long lead lengths – Longer sensor-to-AM16/32 leads result in greater induced and capacitively coupled voltages (cross-talk) between cable wires.
AM16/32 Relay Analog Multiplexer Several enclosures are available for purchase through CSI (models AM-ENC, ENC 12/14, and ENC 16/18). They offer a degree of protection against dust, spraying water, oil, falling dirt, or dripping, noncorrosive liquids. These enclosures contain a mounting plate with 1-inch hole grid suitable for mounting the AM16/32. The enclosures have a cable bushing (AM-ENC has two) to accommodate the sensor lines. These standard enclosures are rain-tight, but not water-proof.
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Appendix A. AM16/32 Improvements The AM16/32 provides the panel switch option of operating in one of two modes. • “4X16” mode - Sixteen channels of four simultaneously enabled terminals (SETs). • “2X32” mode - Thirty-two channels of two SETs. The AM16/32 is designed to do a “break before make” meaning that it advances channels with no momentary connection of the present channel’s sensor inputs with the next channel’s sensor inputs.
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