Campbell Scientific AM25T 25-Channel Solid State Multiplexer - Manual (Page 31)

Appendix B. Differences Between the
AM25T, AM416, and the AM32
The AM25T differs from Campbell Scientific's AM416 and AM32
multiplexers in the following ways:
1. The AM25T cannot be used to multiplex power and is not suitable for
bridge measurements because of the high impedance of the solid state
relays.
2. The AM25T switches 25 sets of 2 lines at time, (HI and LO) (2 x 25),
unlike the AM416 which switches 16 sets of 4 lines at a time (4 x 16).
The AM32 switches 32 sets of 2 lines at a time (2 x 32).
3. The AM25T has a built-in temperature reference RTD for thermocouple
measurements. It is 1000 Ohm RTD and has a temperature specification
of
+/-0.2
°C an α of 0.00385.
4. The AM25T is packaged in an aluminum case that will decrease
temperature gradients across the multiplexer terminal strip. It has a large
aluminum bar through the center of the unit for temperature stabilization
and sensor cable strain relief.
5. The AM25T is smaller than the AM416 and AM32. It is packaged in a
vertical manner for a smaller footprint and requires less space for
mounting.
6. The AM25T has a ground path back to the datalogger for spark gap firing
and sensors shields via the grounding lug on the side. The AM25T
contains terminals and circuitry for sensor shield wires. This circuitry
allows sensor shield wires to be routed through the multiplexer and
grounded at the datalogger.
7. The AM25T contains spark gaps on all inputs and like the AM416
contains diodes between shields and power ground for transient
protection.
B-1