RE: Syncronising triggred data acquisition for Modbus "I/O Intr" records and sscan records

[Mark Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Hi Kuldeep,

 

What you are doing should work without the long detector delay time, but it depends on using the correct type of database links.

 

Can you send your database, perhaps simplified to just illustrate the problem?  Also send the output of camonitor for all of the interesting PVs in the chain.

 

Mark

 

 

From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Kuldeep Joshi via Tech-talk
Sent: Friday, July 16, 2021 11:37 AM
To: tech-talk at aps.anl.gov
Subject: Syncronising triggred data acquisition for Modbus "I/O Intr" records and sscan records

 

Hello,

I am having a Modbus interface, I have disabled polling and I am using MODBUS_READ as a trigger. An ai record  "myData" (with SCAN as "I/O Intr" which holds the data received over Modbus.

 

sseq is used to give start of conversion and check for EOC and send MODBUS_READ and wait for myData to be processed (by checking busy record). In short I am using the sseq record in sscan as a detector trigger.

 

I am using a sscan along with sseq records for triggering and acquiring the data over Modbus. To synchronise the detectors MODBUS_READ command (I am using busy record) and on processing of myData record (I am using myData.FLNK to trigger a bo record to reset the busy record). the sseq record is waiting on this busy before sscan record acquires the detector data.

 

I am always getting N-1th sample instead of the Nth sample. However if I give sufficiently long detector delay time ie of 1-2 sec I am receiving proper data. I am not happy with this workaround

What am I doing wrong?

 

Thank you in advance

 

Regards,

Kuldeep