Rockwell Automation 1790P-4R0 CompactBlock LDX I/O RTD/Resistance Input Module - Manual (Page 46)

Publication 1790-UM002A-EN-P
4-2 Diagnostics and Troubleshooting
Stand Clear of the Equipment
When troubleshooting any system problem, have all personnel remain
clear of the equipment. The problem could be intermittent, and sudden
unexpected machine motion could occur. Have someone ready to operate
an emergency stop switch in case it becomes necessary to shut off power.
Program Alteration
There are several possible causes of alteration to the user program,
including extreme environmental conditions, Electromagnetic Interference
(EMI), improper grounding, improper wiring connections, and
unauthorized tampering. If you suspect a program has been altered,
check it against a previously saved master program.
Safety Circuits
Circuits installed on the machine for safety reasons, like over-travel limit
switches, stop push buttons, and interlocks, should always be hard-wired
to the master control relay. These devices must be wired in series so that
when any one device opens, the master control relay is de-energized,
thereby removing power to the machine. Never alter these circuits to
defeat their function. Serious injury or machine damage could result.
Module Operation vs.
Channel Operation The module performs diagnostic operations at both the module level and
the channel level. Module-level operations include functions such as
power-up, configuration, and communication with a controller.
Channel-level operations describe channel related functions, such as data
conversion and over- or under-range detection.
Internal diagnostics are performed at both levels of operation. When
detected, module error conditions are indicated by the module status LED.
Channel over-range or under-range conditions are reported in the
module’s input data table.