ActiveX CA Server/Client Update Nov Kay-Uwe Kasemir, LANL

ActiveX CA Server/Client 4 –Does Andrew really want this link? 4 Can be used with many Win32 programs: Visual Basic, LabVIEW, Delphi, … 4 Reality: Used with LabVIEW 4 LEDA: 1.5y experience, ~10 PCs, (!)PVs each 4 Other Labs: >25 requests, mostly for the server, though often unclear (non-EPICS users) 4 Requests for new options: –string support –allow passing {value, time} to server

LANL Experience 4 Terrific for small systems –Signal generator, GPIB, new PC: 2 hours! –No need for vxWorks, IOC, boot host, display computer 4 Faster initial development cycle no recompile & reboot, (until turned into distributed system) 4 Easier to learn(?) vs.

LabVIEW Issues 4 Visual programming is limited –“image” gets too big, “wires” tangled –no ASCII import/export no real CVS support, no comparable NI tool no script-generated code from signal list, RDB, Capfast,... –what you see is all you get: IOC’s scanning mechanisms have to be re-implemented with fundamental instructions (loops, delays, …)

LabVIEW Issues 4 Complex logic, many PVs hard to maintain: “sequences” show only one step at a time array handling in for-loops: necessary for bigger systems but misleading (auto-indexing fails for different array sizes)

Performance: Looks OK 4 450Mhz PC: ~0.3ms, send value from LabVIEW to ActiveX CA Server 4 900Mhz: ~0.14ms 4 Main factor: COM (10 10, 100, 500 Hz on 450Mhz Pentium II)

LabVIEW: Polling 4 CA ‘put ’ into PV on ActiveX CA Server...  ActiveX Event is sent with, receiver like LabVIEW has to decide whether to serve the new value, a modified value or keep the old one. 4 VisualBasic can handle events async., LabVIEW can only “WaitForEvent” –User waits for response until LabVIEW’s main loop comes around to service the PV changes –LabVIEW offers threads & semaphores, but even many Nat.Inst. VIs are incompatible. ”Main code” in here!

LabVIEW/PC Issues 4 No remote login into PC 4 LabVIEW 5.1 sometimes crashes during setup of ActiveX connection (runs fine once this succeeds) 4 ActiveX Events: –didn’t work before LabVIEW 5.1 –5.1: still didn’t work originally, it took bulletproof examples for NI support to acknowledge their problem and provide patch, now available from National Instruments’ web site –memory leak in 5.1, supposed to be gone in 6i (not tested) 4 Time stamps not synchronized with other EPICS IOCs –could be called an EPICS fault because IOCs use proprietary protocol

Conclusion (still) Win32-Program (with not too much) data worth serving, e.g. LabVIEW ‘EPICS’ data + ActiveX CA Server