Rockwell Automation 1769-IT6 Compact I/O 1769-IT6 Thermocouple/mV Input Module - Manual (Page 76)

76 Rockwell Automation Publication 1769-UM004B-EN-P - March 2010
Chapter 5 Diagnostics and Troubleshooting
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 versus
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 1769 bus master, such as a
MicroLogix 1500 controller, 1769-ADN DeviceNet adapter, or CompactLogix
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 immediately indicated by the module status
indicator. Both module hardware and channel configuration error conditions are
reported to the controller. Channel over-range or under-range and open-circuit
conditions are reported in the module’s input data table. Module hardware errors
are typically reported in the controller’s I/O status file. Refer to your controller
manual for details.
Power-up Diagnostics At module powerup, a series of internal diagnostic tests are performed. If these
diagnostic tests are not successfully completed, the module status indicator
remains off and a module error is reported to the controller.
If module status
indciator is Indicated
condition Corrective action
On Proper operation No action required.
Off Module fault Cycle power. If condition persists, replace the module.
Call your local distributor or Rockwell Automation for
assistance.