AM16/32B Relay Multiplexer Revision: 4/13 C o p y r i g h t © 1 9 8 7 - 2 0 1 3 C a m p b e l l S c i e n t i f i c , I n c .
Warranty “PRODUCTS MANUFACTURED BY CAMPBELL SCIENTIFIC, INC. are warranted by Campbell Scientific, Inc. (“Campbell”) to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless otherwise specified in the corresponding Campbell pricelist or product manual. Products not manufactured, but that are re-sold by Campbell, are warranted only to the limits extended by the original manufacturer.
Assistance Products may not be returned without prior authorization. The following contact information is for US and international customers residing in countries served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs for customers within their territories. Please visit www.campbellsci.com to determine which Campbell Scientific company serves your country. To obtain a Returned Materials Authorization (RMA), contact CAMPBELL SCIENTIFIC, INC., phone (435) 227-9000.
Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Function.......................................................................1 1.1 1.2 Typical Applications ............................................................................1 Compatibility .......................................................................................2 2. Physical Description..............................
Table of Contents 6.6 Thermocouple Measurement ............................................................. 30 6.6.1 Measurement Considerations ..................................................... 30 6.6.2 Single-ended Thermocouple Measurement ................................ 32 6.6.3 Differential Thermocouple Measurement .................................. 33 6.7 Mixed Sensor Types .......................................................................... 33 6.7.
Table of Contents 6-11. Thermocouple and soil block measurement for CR10X example......34 8-1. Mounting tab hole pattern ..................................................................38 Table 5-1. Single Loop Instruction Sequence......................................................
Table of Contents iv
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.
vi
AM16/32B Relay 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 Campbell Scientific’s AM16/32A 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 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 ENC10/12 (10” x 12”) enclosure is recommended. 1.
AM16/32B Relay Multiplexer FIGURE 2-1. AM16/32B Relay Multiplexer 3. AM16/32B Specifications Power*: Minimum Operating Voltage: Current Drain Quiescent: Active: Unregulated 12 Vdc from –55° to +40°C = 11.3 Vdc from +40° to +85°C = 11.8 Vdc (See FIGURE 3-1 for relay actuation times vs. temperature and supply voltage.) <210 µA 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 Multiplexer Dimensions Length: Width: Depth: 23.9 cm (9.4 in) 10.2 cm (4.0 in) 4.6 cm (1.8 in) Weight: 693 g (1.5 lb) (approx.) Mounting Tab Hole Spacing: 1 x 3 x 9 in. Up to 1/8 in or 3 mm diameter screws (see FIGURE 8-1).
AM16/32B Relay Multiplexer Surge: Complies with IEC61000-4-5, test level 3 (±2 kV, 2 ohms coupling impedance) * Reset and clock protected by 8V varistors; +12V input is protected by +16V transzorb. ** Assumes sequential activation of multiplexers and that each datalogger channel is uniquely dedicated. If your application requires additional multiplexing capability, please consult Campbell Scientific for application assistance.
AM16/32B Relay Multiplexer dataloggers connect to the AM16/32B as shown in FIGURE 4-1 (“4x16” mode). FIGURE 4-1 depicts control connections. Measurement connections are discussed in Section 6, Sensor Hookup and Measurement Examples. The power, ground, reset, and clock connections remain essentially the same regardless of datalogger used. With the CR5000, CR3000, CR800, CR850, CR1000, CR23X, and CR10(X), the datalogger 12 Vdc supply and ground terminals are connected to the AM16/32B 12V and ground terminals.
AM16/32B Relay Multiplexer 4.1.2 Clock Pulsing the AM16/32B “CLK” line high (“RES” line already high) advances the channel. The voltage level must fall below 1.5 Vdc and then rise above 3.3 Vdc to clock the multiplexer. The AM16/32B operates in one of two clocking modes: Mode A—sequentially advances through each relay channel (as long as RESET is HI, relays are closed on each rising CLK edge). A more detailed description of Mode A is provided in Section 4.1.2.1, Mode A.
AM16/32B Relay Multiplexer NOTE If the time between the falling edge of the 5 ms RESET pulse and the next rising edge of RESET or CLK is longer than 125 ms, the AM16/32B will go into Mode A. Section 4.1.2.3, Datalogger Connection/Instruction, includes a portion of a CR1000 program that shows the instructions used to go into Mode B and jump to channel 6. 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.
AM16/32B Relay 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 Multiplexer 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 s/chan x 32 chan)/ 60 s) 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 s/chan x 32 chan)/2 s) x 6 mA = 2.9 mA.
AM16/32B Relay Multiplexer 4.2.1 COM Terminals A CABLE3CBL, CABLE4CBL, 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. The CABLE4CBL is typically used for the 4x16 mode. The CABLE5CBL is recommended for the 4x16 mode when it is desirable to connect both shields. The four terminals dedicated to multiplexer-datalogger connection are located under the blue COM next to the mode switch.
AM16/32B Relay Multiplexer (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. A given SET will typically be connected to the common terminals for 20 ms. With panel switch set to “2x32” mode, the white channel numbers apply.
AM16/32B Relay Multiplexer 5.1 CRBasic Programming The CR5000, CR800, CR850, CR3000, and CR1000 are programmed with CRBasic. The PortSet() instruction enables or disables the multiplexer and the SubScan()/NextSubScan instruction begins/ends the measurement loop. The program must also specifically increment an index variable and use that variable to determine where each measurement is stored.
AM16/32B Relay Multiplexer Units: the unit of time to be used for the SubInterval parameter. A numeric or alphabetical code can be entered. Numeric Alpha Description 0 μsec microseconds 1 msec milliseconds 2 sec seconds 3 min minutes Count: the number of times the SubScan() will run each time the scan runs. Basically, the count parameter is the number of sets on the multiplexer that you will be using for this SubScan() instruction.
AM16/32B Relay Multiplexer Wiring for CR1000 Program Example CR1000 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 Multiplexer 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 5.1.
AM16/32B Relay Multiplexer I=I+1 'The Resistance measurement measures the PRT resistance: Resistance (PRTResist(I),1,mV50,7,Ix1,1,500,True ,True ,0,250,0.01,0) 'With a multiplier of 0.01 (1/100) the value returned is R/Ro (Resist/Resist @ 0 deg) 'the required input for the PRT temperature calculation instruction. NextSubScan Portset (1 ,0) 'Set C1 Low to disable Multiplexer 'Calculate the Temperature from R/Ro: PRT (PRTTemp(1),16,PRTResist(1),1.
AM16/32B Relay Multiplexer # 3 Clock and Delay — With the CR23X and CR10(X) the clock line is connected to a control port. Instruction Do (P86) with the pulse port command (71– 78) pulses the clock line high for 10 ms. Instruction Excitation with Delay (P22) can be added following the Do (P86) to delay an additional 10 ms. When using a 21X or CR7, the clock line may be connected to either an excitation or control port.
AM16/32B Relay Multiplexer First pass: Second pass: Third pass: Input locations 1 2 3 4 1 2 3 5 5 6 4 6 sensor numbers A potential drawback of this technique is that sequential sensors (i.e., those input to the same SET) will not have sequential input locations. #5 Measure — Enter the instruction needed to measure the sensor(s) (see Section 6, Sensor Hookup and Measurement Examples).
AM16/32B Relay Multiplexer GENERALIZED “4x16” MODE PROGRAM LOOPS FOR THE CR23X, CR10(X), 21X, and CR7 21X SAMPLE PROGRAM CR7 SAMPLE PROGRAM CR10(X), CR23X SAMPLE PROGRAM * * * 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 "4X16"MODE MODE AM16/32 IN IN "4X16" CR23X CABLE SHIELD 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 CABLE SHIELD SHIELD COM COM FIGURE 5-4.
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 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 singleended analog input channel. The COM signal-ground line is tied to “ ” at the CR23X, 21X, or CR7, and to “AG” at the CR10(X).
AM16/32B Relay Analog Multiplexer 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. Observe H to H and L to L from sensor to multiplexer to analog input. In “4x16” mode up to 32 differential sensors can be measured by two differential datalogger channels in this way.
AM16/32B Relay Analog Multiplexer CR23X/ CR800/ CR850/ CR1000 21X/ CR7 CR10(X) CR3000/ / CR5000 EX E E VX H H H L L L "4 X 16" Mode 0 COM H (ODD) ODD H H COM L ODD L L COM H (EVEN) EVEN H COM L EVEN L AG G CABLE MUXSIGNAL SHIELD COM SHIELD SENSOR SHIELDS FIGURE 6-4. Potentiometer hookup and measurement (using CABLE4CBL cable) 6.3.
AM16/32B Relay Analog Multiplexer CR23X/ CR800/ CR850/ CR1000 21X/ CR7 CR10(X) CR3000/ / CR5000 EX E E VX H H H L L L "4 X 16" Mode 0 COM H (ODD) ODD H H COM L ODD L L COM H (EVEN) EVEN H COM L EVEN L AG H H H H L L L L G COM SHIELD SENSOR SHIELDS FIGURE 6-5. Four wire half bridge hookup and measurement The CR5000 and CR3000 also have current excitation channels which allow a resistance measurement.
AM16/32B Relay Analog Multiplexer analog ground. Up to sixteen full bridges may be multiplexed through the AM16/32B. 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.
AM16/32B 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 6-8 and FIGURE 6-9, two reference junction configurations are possible: 1) reference located at the datalogger or 2) reference at the AM16/32B.
AM16/32B Relay Analog Multiplexer 21X/ CR7 CR10(X) CR3000/ CR800/CR850/ / CR23X/CR1000/ 0 CR5000 H H H L L L H H H L L L "4 X 16" Mode CU CO CU CO G COM ODD H ODD H COM ODD L ODD L COM EVEN H EVEN H COM EVEN L EVEN L CU CO CU CO SENSOR SHIELDS COM FIGURE 6-8.
AM16/32B Relay Analog Multiplexer Thermal Gradients — Thermal gradients between the AM16/32B’s sensor input terminals and COM terminals can cause errors in thermocouple readings. For example, with type T thermocouples, a one degree gradient between the input terminals and the COM terminals will result in an approximate one degree measurement error. Installing the aluminum cover plate (FIGURE 6-10) helps to minimize gradients.
AM16/32B Relay Analog Multiplexer • Multiplexer to Datalogger Wiring — If the reference junction is at the datalogger, then the wire that connects the COM ODD H, COM ODD L, and COM EVEN H terminals to the datalogger should be of the 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.
AM16/32B Relay Analog Multiplexer 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 6-11. Thermocouple and soil block measurement for CR10X example CR10X Example Program — Thermocouple and Soil Block Measurement *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,1,
AM16/32B Relay Analog Multiplexer 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, Campbell Scientific recommends the use of cabling having Teflon, polyethylene, or polypropylene insulation around individual conductors. You should not use cables with PVC insulation around individual conductors (PVC cable jacket is acceptable).
AM16/32B Relay Analog Multiplexer 8.1 Mounting Tabs The AM16/32B has mounting tabs allowing attachment by four screws. See FIGURE 8-1 dimensions. 1 in 2.54 cm AM16/32B AM16/32 33 in in 7.62 7.62 cm cm 9 inin 9.4 22.9 cm 23.9 cm FIGURE 8-1. Mounting tab hole pattern U-bolts are provided with enclosure to attach to a 1.25 inch (32 mm) diameter pipe. An enclosure may also be lag-bolted to a wall or other flat surface. 8.
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.
Appendix A.
Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com • info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za • cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA) PO Box 8108 Garbutt Post Shop QLD 4814 AUSTRALIA www.campbellsci.com.au • info@campbellsci.com.au Campbell Scientific do Brasil Ltda. (CSB) Rua Apinagés, nbr.
