System Operation

At power-up, the thermocouple module performs a check of its

internal circuits, memory, and basic functions. During this time the

module status LED remains off. If no faults are found during the

power-up diagnostics, the module status LED is turned on.

After power-up checks are complete, the thermocouple module waits

for valid channel configuration data from your SLC ladder logic

program (channel status LEDs off). After configuration data is written

to one or more channel configuration words and their channel enable

status bits are set, the channel status LEDs go on and the

thermocouple module continuously converts the thermocouple or

millivolt input to a value within the range you selected for the enabled channels.

Each time a channel is read by the module, that data value is tested by

the module for a fault condition, i.e. open circuit, over range, and

under range. If such a condition is detected, a unique bit is set in the

channel status word and the channel status LED blinks.