OkiePC
Lifetime Supporting Member
Guys, thanks so much for the detailed and informative responses!
Regarding these faults, under what circumstances would you actually stop the process and wait for a repair vs. simply mute the sensor? If a sensor signal fails that is required to go to the next step in a sequence, do you just program in a time delay overrride which can be activated via the hmi or just have the operator acknowledge the fault on the hmi then mute the sensor from that point on?
I'm not really sure i understand how you can write the program to mute the sensors in advance in case One consistently times out.
Thanks!
It depends on the systems tolerance to expected errors if you substitute expected sensor information.
I once wrote some sorting logic that mapped the contents of a conveyor with encoder feedback into a data file, and contolled the merge of 8 machines onto a belt at various drop points, and then being discharged among four output lines. In the office, testing my pointer based conveyor map logic, I wrote a pseudo encoder program with ramping matched to the drive command.
In the field, when the encoder failed, I had added a method to switch on the encoder emulator math and it worked flawlessly, even when stopped and started, (because my test code was modelled after the real machine to accurately test my design)
It ran in that mode for a week while they got new drive parts ready, and I went ahead and added logic to switchover within a few seconds of failure, and switch back when the encoder signal was restored automatically with a Fault: Encoder Loss making them acknowledge the fault and restart the line. When the encoder signal was restored, it became a Warning (but no stoppage) to the Panelmate when the encoder signal returned to normal.
These were fully assembled green tires being dropped on a moving belt and they needed to be close together but not touching or they would stick to each other.
If you ignore a sensor will someone get hurt?
If you ignore a sensor will your machine be damaged?
If you ignore a sensor will your product be compromised?
After answering no to all the above may qualify some sort of fallback or failover mode.
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