Field-Side Diagnostics; Features Specific To 1715-Ob8De Digital Output Modules - Rockwell Automation Allen-Bradley 1715-AENTR User Manual

Chapter 4 Digital I/O Operation
Features Specific to
1715-OB8DE Digital Output
Modules
124
1. On the Module Properties dialog box, click the Configuration tab.
2. Do one of the following:
• Check a checkbox to enable COS for a specific point for either Off to
On or On to Off.
• Clear the checkbox to disable the COS for a specific point.
3. Click OK.
See Threshold Values for Digital Inputs on page 261
threshold configurations.

Field-side Diagnostics

If using the 1715-IB16D thresholds, you are responsible for designing a circuit
that provides unique voltage levels for Wire OFF, OFF, ON, and shorted to
24V DC. This typically involves an inline and shunt resistor. Typical values for
the inline resistor are 3.9 k. A typical value for the shunt resistor is 15 k. This
generates an OFF voltage of 5V DC and an ON voltage of 14V DC if the supply
voltage is 24V DC.
The digital input module can detect the voltage level, much like an analog
input module. There are no circuit tests on field wiring. You define your
diagnostic granularity by using custom thresholds that are built in to the
channel configuration. For full diagnostics, you design a circuit for which the
OFF state is, for example, 5V DC, and the ON state, which is, for example, 15V
DC. Wire OFF creates 0V DC, which falls below the OFF threshold, and
OpenWire fault status is set HI. A short to 24V DC is above the ON threshold,
and Short Circuit fault status is sent HI.
The features that are described in this section are available on all 1715 digital
output modules.
Rockwell Automation Publication 1715-UM001J-EN-P - December 2020
for setting custom