Re: [EXTERNAL] Modbus and SScan acquisition synchronisation and timestamp query

["Kasemir, Kay via Tech-talk" <tech-talk at aps.anl.gov>]

Hi:

Good question, I’ve been wondering about this as well!

When I had N records that all read from the same device via SCAN=I/O Intr, I’ve set the “TPRO” flag and that way saw in which order they are processed. Then I added an FLNK from the one record processed last to the record or chain of records that should process next to use the information just read from the device.

That “works” as long as your device support always reads items from the device and then issues the I/O Intr updates of the associated records in the same order. This was the case for the specific device that I used, but isn’t generally given.  

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Hello,

I am having a device communicating over Modbus/TCP with four analog input channel

I am using these individual channels with ai records and SCAN in I/O Intr mode.

These four channels are used as detector PV's in SScan record.

I wanted to trigger the Detector acquisition only after all the four ai PV are processed (i.e. after I/o Intr processing of ai record).

Is there any way to do this and can I get the time stamp of the modbus read/write operation.

I am using EPICS 7 with modbus 3.3 asyn 4.42 streamdevice 2.8.22

Thank you in advance.

Regards,

Kuldeep