Experimental Physics and
Industrial Control System

Dear Core Developers;

 

I and my colleagues in SLAC, are recently studying about the named event and its new API.

It is helpful us.  

LCLS1 used up all of 255 numbered events in event system, and we need more events for LCLS2.

Since, our timing system need to work for both LCLS1 and LCLS2, we want to extend the number of events.

The named event removes the cap of 255 events.

 

But, it also brings some following issues:

 

When we generates event, we latched timestamp and pulse id for the event.

If we set TSE>0, the generalTime allows to retrieve the timestamp for PVs.

 

1.       There is no limit for the number of event, but TSE has limits -2, -1, 0, …. ,255

2.       Event can have name (not numberic) but, TSE is still numeric field

 

Since, TSE is still numeric field, we found a quick solution.

We are going to assign  “1” to  name “255” named event for LCLS1 and higher number string (ex, “301”, “302”..) for LCLS2.

We are going to modify a macro in GeneralTime which limits the maximum number of event to support the higher number events. We are going to extend supporting event number in our Event Provider function.

Please, let me know if it is acceptable.

 

I am also wondering about future plan for the TSE field generalTime Event Provider.

Event has name, but TSE is numeric. It looks like we are in the middle of changes.

I would like to suggest, if we can change TSE field to accept string. Then, we can solve all of above issues.

For the backward compatibility for the string TSE field, we can use string for certain function:

Ex,          “-2”: driver layer updates record timestamp field

               “-1”: best event provider gives record timestamp

                “0”: current time provider gives timestamp

                Named string: best event provider gives timestamp which corresponds to the particular event.

 

 

Thank you for your concern.

 

Best regards,

Kukhee

 

 

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Kukhee Kim

SLAC National Accelerator Laboratory

2575 Sand Hill Rd, MS 64

Menlo Park, CA 94025

Email: [email protected]

Phone: (650)926-4912

Fax:   (650)926-3800