ATTENDEES:
Sheng, Qing, Chris, Matt, Rick, Diane
TOPICS:
30, 60Hz and 120Hz BLD
The current e-beam BLD is limited to providing data at most 30Hz. In May LCLS will likely not run at 120Hz, but may be able to provide 60Hz beam rate. It was generally agreed that if 60Hz beam rate is available then experimenters will want it.
It was also generally agreed that BLD data needs to be available at beam rate. IN May the feedbacks that were supposed to supply the e-beam energy and position data at 120Hz will not have been commissioned - mostly likely they will not be running until July. This means the BLD must continue to do a rough calculation of those parameters, but must be able to do this at 60Hz.
BLD Design
The e-beam BLD IOC will required three network interfaces instead of the expected two interfaces. They are 1) to the LCLSFNET e-beam multicast network to receive 120Hz data, 2) to the LCLSCA e-beam channel access network to receive coefficients for the rough calculations and 3) to the PCSD multicast network to send the results. I have learned from Till Straumann that we do have a recommended PMC card and RTEMS driver to supply the 3rd network interface needed. The e-beam group will estimate the effort and schedule to add the new interface and let you know when we can have a 60Hz/120Hz BLD ready.
Errors with the current BLD
The current BLD drops a pulse (once every 10 second at most).
Another related problem is that when data from a pulse is dropped, then the next pulse timestamp reported is either a copy of the last one reported, or possibly two pulse counts back (chris was not certain which - he will have to look at some records to let us know
We expect this problem to go away when the BLD is integrated with FCOM and receives its data from the e-beam fast network.
Chris and Matt also had some concerns with packet recieving within their own network and weren't sure if it was related to the BLD or not. this needs further discussion
ACTION ITEMS:
Qing - estimate time and effort needed to add 3rd NIC to BLD and complete the integration with FCOM.