Rockwell Automation 1771-QB Linear Pos. - Manual (Page 34)

Hardware Description
Chapter 4
4Ć5
Terminals 13 through 26 on the module’s wiring arm provide connection points
for discrete input signals. Seven terminals (for each loop) connect to seven
discrete inputs.
The use of these inputs is optional. If you do not want to use them, you can
disable them through the parameter block. (See Chapter 7.) If you disable the
inputs:
the hardware stop input is deactivated (you do not have to tie it high)
the auto/manual input defaults to auto
the programmable controller programs can still read the status of the discrete
inputs in the status block
Because the programmable controller programs can still read the status of the
discrete inputs, by disabling them you can redefine them for your own purposes.
Here are the requirements of the discrete inputs:
low signal 0 to 4 VDC
high signal 10.0 to 30.0 VDC
peak input current 8 mA at 12 VDC
16 mA at 24 VDC
The discrete inputs are configured as current sinks. To reduce heat dissipation,
the module turns the discrete input currents off between samples at a 20% duty
cycle every 2 ms.
Each discrete input has an internal pull-down resistor. If the device that you
have connected to an input provides a high signal, the device must source
current through the pull-down resistor. Figure 4.3 is a simplified schematic of a
discrete input circuit.
Discrete Inputs