Datalogger to am25t wiring – Campbell Scientific AM25T 25-Channel Solid State Multiplexer User Manual

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AM25T Solid State Multiplexer

U-bolts are used to attach the enclosures to a 1.25" NPT pipe. The enclosure
may also be lag-bolted to a wall or similar flat surface.

Fasten the AM25T to the enclosure backplate. Securely fasten the leads to the
strain relief flange running between the AM25T terminal strips and install the
cover to reduce temperature gradients during thermocouple measurements.

3. Datalogger to AM25T Wiring

When powering the AM25T from the same battery as the datalogger, connect
the datalogger to the AM25T as shown in Table 3-1. Two CABLE4CBL-L
cables typically carry control, power, and measurement signals between the
AM25T and the datalogger.

Do not reverse the polarity of the +12 Volt and Ground
leads. Damage to the multiplexer, sensors, and
datalogger will occur.

WARNING

A separate battery can be used to power the AM25T. A separate battery might
be used when the AM25T is installed some distance from the datalogger.
Ground must be connected between the datalogger and the AM25T (Figure 2).

When leads in excess of 152 m (500 feet) are used to connect the datalogger to
the AM25T, it may be necessary to compensate for the drop in RTD excitation
voltage (program example 4).

All AM25T inputs are spark gap protected. To ensure that
the spark gaps fire, the large ground wire between the
AM25T and datalogger must not be greater than 152 m
(500 ft). In applications where lightning protection is not
required, limit the cable length between the AM25T and
datalogger to 305 m (1000 ft).

Caution

TABLE 3-1. Datalogger to AM25T Wiring

Function

AM25T

CR10(X)

21X/CR7

CR23X

CR800,
CR850,
CR1000,
CR3000,
CR5000,
CR9000X

+12V Power

12 V

Power and Shield Ground

G G

Clock

CLK

Control Port

Reset

RES

Control Port

RTD

Excitation

EX Excitation Excitation Excitation Excitation

Analog Ground

Common High

Diff. Chan. H

Common Low

Diff. Chan. L