Permanently read variable

[joelprasad]

Hello Team,
If a variable is enabled for permanently read variable how is that variable polled by Zenon. (Time interval)?

[joelprasad]

Hi Joel,

I believe that the 0.5s update time refers to the availability to an external DDE client, which is also enabled with this property.

The polling time by the drivers is as I explained earlier. The runtime does not poll the drivers, it gets changes from the driver immediately (spontaneously), once the driver detected a change.

Best regards,
Mark

Thank You Mark.

[markclemens]

Hi Joel,

There is no general - fits all situations - answer to your question.

This setting ensures that the runtime always requests the variable from the driver, regardless if it is currently needed (e.g. displayed in a screen) or not.

The driver, depending on the settings in the driver configuration, the driver capabilities, the communication protocol used, the configuration of the remote PLC / IED / RTU, will communicate the variable through polling or spontaneous communication.

If polling is used by the driver, the interval is defined in the driver configuration. Either a global update (polling) interval is used for all variables or up to 4 different polling interval priorities are used.

Best regards,
Mark

[joelprasad]

Hi Joel,

There is no general - fits all situations - answer to your question.

This setting ensures that the runtime always requests the variable from the driver, regardless if it is currently needed (e.g. displayed in a screen) or not.

The driver, depending on the settings in the driver configuration, the driver capabilities, the communication protocol used, the configuration of the remote PLC / IED / RTU, will communicate the variable through polling or spontaneous communication.

If polling is used by the driver, the interval is defined in the driver configuration. Either a global update (polling) interval is used for all variables or up to 4 different polling interval priorities are used.

Best regards,
Mark

Thank You Mark for your response.
Its mentioned in the property help of Permanently Read Variable that the update time is 0.5 sec. So whether the polling would be based on polling interval set in the driver or would it be 0.5 sec. 
I have attached the screenshot for the same.

[markclemens]

Hi Joel,

I believe that the 0.5s update time refers to the availability to an external DDE client, which is also enabled with this property.

The polling time by the drivers is as I explained earlier. The runtime does not poll the drivers, it gets changes from the driver immediately (spontaneously), once the driver detected a change.

Best regards,
Mark

[joelprasad]

Hi Joel,

I believe that the 0.5s update time refers to the availability to an external DDE client, which is also enabled with this property.

The polling time by the drivers is as I explained earlier. The runtime does not poll the drivers, it gets changes from the driver immediately (spontaneously), once the driver detected a change.

Best regards,
Mark

Thank You Mark.