B873-002 and B875-002 Modules
The B873-002 and B875-002 are analog input modules that can be used with 984 programmable controllers. The only difference between the two modules is that the B873-002 has four input channels and the B875-002 has eight input channels.
The module can be set to produce a data value in the standard range (0000 to 4096) or the elevated range (4095 to 8192). It accepts inputs of 1.0 to 5.0 V or 4 to 20 mA. (Refer to
B873-002 and B875-002 Field Connections).
The input is converted to a numerical value, ranging from 0001 to 4095 or 4096 to 8191. Values of 0000, 4095, 4096, or 8192 indicate invalid data and a possible problem. (Refer to the
Data Value Reference Chart). The value is directly proportional to the input signal. For example, an input voltage of 3.0 V causes the module to send a value of 2048 (standard). Or the input could be 12 mA, which would produce a value of 6144 (elevated). (Refer to
Input to Data Value Conversion).
NOTE: No voltage or current on an input channel produces a data value of 0000 (standard) or 4095 (elevated).
The PLC polls the module and places the values into designated (3x) input registers.
Each time the module is powered up, it:
1
performs diagnostic tests
2
resets the input latches
3
presents a value of 0000 to the controller for each channel; this value is present for approximately 3 s after power up
4
starts converting the inputs according to the schedule found in the B873-002 and B875-002 Throughput Rate 
