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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. The low sides of each thermocouple are

multiplexed in common through terminal EVEN L.

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.

If the reference junction is at the AM16/32B (CSI 107 thermistor,

RTD, etc.), then copper wire should be used to connect COM

terminals to the datalogger.

6.6.3 Differential Thermocouple Measurement

AM16/32B panel switch set to “2x32” mode.

Multiplexer to Datalogger wiring - The wire types here can be

handled in one of two ways. If a reference junction (107 thermistor,

or RTD, etc.) is at the AM16/32B, then one copper wire may be run

between the COM terminals of the multiplexer and the datalogger

input channel.

If the reference junction is at the datalogger, then matching

thermocouple wire should be run between the COM terminals of the

multiplexer and the differential input channel on the datalogger

(observe TC wire polarity).

6.7 Mixed Sensor Types

In applications where sensor types are mixed, multiple hook-up

configurations and programming sequences are possible. Please

consult CSI for application assistance if you need to multiplex

markedly different sensor types in your application.

6.7.1 Mixed Sensor Example: Soil Moisture Blocks and

Thermocouples

AM16/32B panel switch set to “4x16” mode.

In this example, 16 thermocouples and 16 soil moisture blocks will be

multiplexed through the AM16/32B. One thermocouple and one soil

moisture block are input into each SET.

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Campbell AVW1 Spezifikationen Seite 40