Rockwell Automation 1769-OF4 Compact Analog Output Module - Manual (Page 44)

44 Publication 1769-UM020A-EN-P - December 2009
Chapter 4 Module Diagnostics and Troubleshooting
Activate Devices When Troubleshooting
When troubleshooting, never reach into the machine to actuate a
device. Unexpected machine motion could occur.
Stand Clear of the Machine
When troubleshooting any system problem, have all personnel remain
clear of the machine. 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 to the machine.
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 program on an EEPROM or
UVPROM memory module.
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.