Rockwell Automation AADvance Controller Troubleshooting and Maintenance Manual - Manual (Page 37)

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Document: 553634
(ICSTT-RM406F_EN_P) Issue: 089:
3-15
On power up or module insertion, a module de-energizes all channels and they remain de-energized
until command states are received from a running application.
Group Output Module Shutdown
As long as one module in a group continues to receive updated command state values from a running
application within the PST, each channel is driven according to its commanded state. This covers the
situation when only one module out of a pair goes into shutdown mode with some channels energized
(from a hold last state setting). This makes sure that these channels do not get stuck energized, and
that the remaining module is able to energize or de-energize these channels according to the
commanded state received from a running application.
Understanding the State Variable (<tagname>.STA)
The state variable (<tagname>.STA) is one attribute of the full structure for input and output channels.
The variable reports a numeric value (from 1 to 7) which reflects the current state of the channel.
States 2 and 4 represent normal operation for digital inputs and outputs; state 3 represents normal
operation for an analogue input. The other states represent a fault.
A digital input channel without line monitoring can detect and report states 2, 3, 4, 6 and 7, but cannot
recognize an open circuit or short circuit. A line monitored input can detect and report every state,
including an open circuit or short circuit. Analogue input channels are always line momitored.
The state variable updates in real time. The fault diagnosis procedures for field faults use the value of
the state variable.
Correlation of LEDs with State Variable for a Digital Input