Controller Fault 1

[soroshrad1]

Hi.
I,ve a problem for detecting a controller faults.I mean what should we do to know that our controller is ok and works properly?
For example, in a process a flow controller has a problem so how we can detect this problem?

 

[danw2]

1) Most microprocessor driven devices have some form of SELF TEST which checks to see if all I/O cards run error free. Typically, a watch-dog timer is used and needs to be reset periodically. A watchdog timer timeout will cause an error, and shut down the processor if not reset within a predetermined period of time. The failure to reset the timer indicates that the logic is not being scanned normally.

2) The process automation controller (PAC) that I'm working with at the moment has a System Monitor function block:

Description:
The Analog System Status Block is a function block and is part of the Alarm/Monitor category. It provides read access to controller status values including those related to the Analog execution cycle.
The output may be connected to function block inputs. The outputs may also be connected to signal tags for operator interface monitoring.

Analog System Status Block Outputs; Output Descriptions

CYCTIME Control Block Cycle Time in seconds

CYCMINS Control Block Cycle Time in minutes

NEWSTART Newstart is ON for one full cycle of control block execution, following a New start of the system. For example: starting after a change from program to run.

RESTART Restart is ON for one full cycle of control block execution, following power up. [Warm Start}

ALM ACTIV Alarm Active is ON if any operator panel alarm is ON.

ALMUNACK Alarm unacknowledge is ON if any operator panel’s alarm is unacknowledged.

HWOK Hardware OK is ON if there are no faults. HWOK is set to off when a Rack Monitor Block's RACK OK pin is off.

LOWBTRY Low Battery is ON if the battery is low, Off when battery is good.

HI TEMP High CJ Temperature is ON if the CJ temperature is high on any rack.

MSTR FAIL Communications Failure is ON when Modbus master diagnostic is not good

BAD BLOCK Bad Block is ON when one or more blocks are not operating properly. Any function block monitor window which indicates a block status other than "OK" will cause the Bad Block pin to energize. For example: forced outputs (analog or digital), math errors (divide by zero), un-configured I/O blocks (rack/slot/channel) and PID block, a PV over/under the configured range limits. HC Designer can locate forced blocks; however, it cannot advise the user which block(s) are causing the Bad Block indication.

LOCKED Controller locked in current mode by switch position.

TIME OFF Number of seconds power was turned off. Valid for one cycle of control blocks execution following power up. Then it is cleared to zero.

DS LIMIT ON when the configured storage warning limit is exceeded. OFF when the storage capacity falls below the warning limit.

RSV AVAIL C70R controllers only. ON when the Reserve CPU is available for failover. OFF when the Reserve CPU is unavailable for failover.

Power Supply Diagnostic
When monitoring the ASYS block a Power Supply Diagnostic indicates which, if any, rack has a power supply problem. See Rack Diagnostics Power Supply Diagnostics for more info.

When connected, the development software displays a status screen:

Your controller probably does something similar.