Hi,
We have a requirement to check the controller good execution status (power is up & download status is good) in a module logic expression to drive a DO to indicate .
Can anyone please suggest which diagnostic parameter/s can be used for this purpose?
I have already checked following:
OINTEG: (Overall Integrity) Active for Bad IO or modules also. Cannot be used solely for this purpose.
LASTDNLDSTAT: (Last Download Status) Not available when power down.
HW/SW REV: (Revision) Does not indicate download status.
COMM PRI/SEC OINTEG: Only communication integrity. Does not indicate the download status. Not enough to check comm status with individual/perticular node.
Can I use "FRETIM < 100%" to check the controller status?? (This is also not available when power is down...)
Thanks in advance for your answers!
Not completely sure what you're trying to achieve.
From what I understand, there are 2 separate problems. Power and downloaded configuration? (The control module monitoring the status of a controller should run in a different controller. If it runs in the same controller use a fail-safe principal for the DO-loop (i.e. problem = open loop).)
For checking power:
-DeltaV Power supplies have an alarm relay that can be used for checking if there is power. Connected to DI-card of another controller gives 1st indication of power-problems.
-In general, if any of the parameters you have mentioned cannot be read, there is a problem. Either with power or communication.
Checking download status:
-Obviously, controllers will only do an automatic download when the cold restart option is enabled. And on older DeltaV versions, the cold restart memory needs to manually updated after each configuration change.
-Controllers have 4 hardware-alarms that can be used for health monitoring of the controller itself.
-The OINTEG parameter goes to 'bad integrity' already when a valve is interlocked for instance. Not suitable to use.
-FreTim is usually below 100%, so also not suitable.
-There are 3 controller parameters that show if there is 'module-slippage', so if modules aren't executed in 1 controller-cycle. These are CTRL_NAME/CONT/LPCONTIME, CTRL_NAME/CONT/MPCONTIME and CTRL_NAME/CONT/HPCONTIME. They should all be 100% all the time, else there are problems with processor loading.
-I would say these 3 parameters combined with LASTDNLDSTAT can be used to confirm the configuration is downloaded and running.
In reply to Robert Rijnders:
Hi Robert,
Thanks for your response!
Yes, the monitoring of this controller status will be done in seperate controller.
Actually, We have a controller with HW IO's & other few with MODBUS/TCP-IP comm with 3rd party system. The logic required was to trigger a DO, when certain condition is active & communication WATCHDOG is active.
We monitor the communication line & 3rd party PLC to calculate watchdog. But when the controller is down, it is also watchdog condition. This condition is detected by 3rd party package, but they do not have this DO. We do not have comm link with this 3rd party system on the HW IO controller.
So, available option is: to check the controller status internally & generate the "Watchdog due to controller failure" within deltaV. One way is to generate a counter & check in another controller the changing value. But I thought it will be an overkill for this requirement.
Hence, I was checking if any diagnostic parameter is available readily for this purpose...
Regards,
Amod Bobade.