mpalmer1223
Member
Hi, newbie here [you have been warned 
]
I have a basic application using RSLogix 5000 [v20] and FactoryTalk View ME 6.10. I have imported the PLC tags at FTVME and all is basically working, except I see some intermittent flicker in my HMI for a few of the inputs I am displaying. [setting the tag update at 100ms helps a lot, but not completely].
The data being displayed has both a status tag and an "actual reading" tag associated with it. [for example, when status is "open" or shorted", then "actual reading" is not meaningful content. If status is "ok", then "actual reading" *is* meaningful.]
The ladder application uses COP instruction to move a set of status values on rung X, then a set of mated actual values on rung X+1, into the user defined data type object that the HMI is reading.
I am wondering if it is possible that the HMI's reads are asynchronous to the ladder scan such that, from time to time, it could be reading a new status and an old "actual value", say, if the HMI read was processed at PLC between rung X and rung X+1 of the scan.
[1] is this asynchronous bevaior what is causing the flickering?
[2] is there a generalized design pattern or built in mechanism to cause HMI tag access to occur only *outside* of a given ladder scan at the plc?
Thanks much,
-Mike
]I have a basic application using RSLogix 5000 [v20] and FactoryTalk View ME 6.10. I have imported the PLC tags at FTVME and all is basically working, except I see some intermittent flicker in my HMI for a few of the inputs I am displaying. [setting the tag update at 100ms helps a lot, but not completely].
The data being displayed has both a status tag and an "actual reading" tag associated with it. [for example, when status is "open" or shorted", then "actual reading" is not meaningful content. If status is "ok", then "actual reading" *is* meaningful.]
The ladder application uses COP instruction to move a set of status values on rung X, then a set of mated actual values on rung X+1, into the user defined data type object that the HMI is reading.
I am wondering if it is possible that the HMI's reads are asynchronous to the ladder scan such that, from time to time, it could be reading a new status and an old "actual value", say, if the HMI read was processed at PLC between rung X and rung X+1 of the scan.
[1] is this asynchronous bevaior what is causing the flickering?
[2] is there a generalized design pattern or built in mechanism to cause HMI tag access to occur only *outside* of a given ladder scan at the plc?
Thanks much,
-Mike
