Rockwell Automation 1746-FIO4V SLC 500 Fast Analog I/O/ User Manual - Manual (Page 76)

Publication 1746-UM009B-EN-P - September 2007
76 Maintenance and Safety
Safety Considerations
When Troubleshooting Safety considerations are an important element of proper
troubleshooting procedures. Actively thinking about the safety of
yourself and others, as well as the condition of your equipment, is of
primary importance.
Refer to the Installation and Operation Manual for Fixed Hardware
Style Programmable Controllers, publication 1747-6.21, or SLC 500
Module Hardware Style User Manual, publication 1747-UM011, for
additional information on troubleshooting.
Follow these suggestions when troubleshooting your SLC 500 system.
Indicator Lights – When the red LED indicator 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.
When troubleshooting, pay careful attention to this general warning.
Program Alteration – There are several causes of alteration to the
user program, including extreme environmental conditions,
Electromagnetic Interference (EMI), improper grounding, improper
wiring, 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 – Circuits installed on the machine for safety reasons,
like over-travel limit switches, stop pushbuttons, 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.
WARNING
Never reach into a machine to actuate a switch since
unexpected machine motion can occur and cause injury.
Remove all electrical power at the main power disconnect
switch before checking electrical connections or inputs/outputs
that cause process actuation or machine motion.