AM16/32B without lid, glam view
AM16/32B without lid, front angle view
AM16/32B without lid, front view
AM16/32B without lid, glam view AM16/32B without lid, front angle view AM16/32B without lid, front view
AM16/32B 16-channel or 32-channel Relay Multiplexer

The AM16/32B multiplexer significantly increases the number of sensors that you can measure with a Campbell Scientific data logger. It interfaces with the data logger and adds terminals so that you can wire additional sensors of almost any type.

Depending on sensor type, the AM16/32B can multiplex 16, 32, or 48 sensors. Up to six AM16/32Bs may be connected to the same data logger, depending on the number of control ports and analog inputs available.

The AM16/32B either multiplexes 16 groups of four lines (a total of 64 lines) through four common (COM) terminals. Alternatively, a manual switch setting allows the AM16/32B to multiplex 32 groups of two lines (also a total of 64 lines) through two COM terminals. A cable connects the common terminals to data logger analog inputs, excitation channels, or ground as required by the sensor. The data logger controls the multiplexer using two control ports, or one control port and one excitation channel.

Electrical Surge Protection

The equipment is protected from electrical surges through the use of gas tubes on all the inputs, as well as the ground lug. In addition, the clock and reset are protected by 35 V varistors, the 12V control terminal is protected by an 18 V TVS, and there is a 35 V varistor between the shield ground and the ground lug.


-NOTE- Reset and clock protected by 8 V varistors; +12 V input is protected by +16 V TransZorb.
Power Unregulated 9.6 to 16 Vdc
Scan Advance Occurs on the leading edge of the clock pulse transition (from below 1.5 V to above 3.3 V)
Minimum Clock Pulse Width 1 ms
Maximum Actuation Time for Relay 20 ms
Relay Operation Break before make
Initial Relay Resistance, Closed 0.1 ohm
Maximum Switching Current 500 mA 
(Switching currents greater than 30 mA [occasional 50 mA current is acceptable] will degrade the contact surfaces of the mechanical relays and increase their resistance.This will adversely affect the suitability of these relays to multiplex low voltage signals.Although a relay used in this manner no longer qualifies for low voltage measurement, it continues to be useful for switching currents in excess of 30 mA.)
Maximum Switching Voltage 50 Vdc 
A voltage divider such as the VDIV10:1 may be needed between the AM16/32B and the data logger to stay within the input limits of the data logger channel.
Minimum Contact Life 5 x 107 operations
Maximum Contact Voltage Rating 70 V
Maximum Voltage 8 Vdc (clock level)
CE Compliance
  • EN 61326:1998
  • EN 55022:1998 Class B
Surge Complies with IEC61000-4-5, test level 3 (±2 kV, 2 ohm coupling impedance)
Operating Temperature Range
  • -25° to +50°C (standard)
  • -55° to +85°C (extended)
Dimensions 23.9 x 10.2 x 4.6 cm (9.4 x 4.0 x 1.8 in.)
Weight ~680 g (~1.5 lb)


Air Discharge Complies with IEC61000-4-2, test level 4 (±15 kV).
Contact Discharge Complies with IEC61000-4-2, test level 4 (±8 kV).

Typical Current Drain

Quiescent < 210 µA
  • 6 mA (typical in 2x32 mode)
  • 11 mA (typical in 4x16 mode)

Reset Levels

Inactive < 0.9 V
Active 3.3 to 8 V


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