Rockwell Automation 1746-XXXX SLC 500 4-Channel Analog I/O Modules User Manual - Manual (Page 90)

Publication 1746-UM005B-EN-P - June 2004
7-2 Maintenance and Safety
Safety Considerations
When Troubleshooting The following section describes several safety areas you should be
aware of when troubleshooting your SLC 500 system.
Indicator Lights - When the red LED on the analog module is
illuminated it indicates that 24V dc power is applied to the module.
Activating Devices When Troubleshooting - When
troubleshooting, never reach into the machine to actuate a device.
Unexpected machine motion could occur. Use a wooden stick.
Stand Clear of Machine - When troubleshooting any SLC 500 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 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 the
program has been altered, check it against a previously saved
program on an EEPROM or UVPROM memory module.
Safety 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.
ATTENTION
Never reach into a machine to actuate a switch since
unexpected machine motion can occur.
Remove all electrical power at the main power
disconnect switches before checking electrical
connections or inputs/outputs causing machine
motion.