Experimental Physics and
Industrial Control System

Andrew Wagner <[email protected]> · Mon, 13 Sep 2010 17:12:56 -0700

Hey Eric, 

After doing some homework with the Application Developer's guide I came to the same conclusion. Pushing data with FLNKs produces the desired result. Thanks for the help. 

Andrew

On Sep 13, 2010, at 4:23 PM, Eric Norum wrote:

> When you have records performing asynchronous input it is often better to "push" data through a sequence of records rather than to "pull" it as you are now doing.
> 
> Could you restructure your database to have the $(MUX)VOLT:Chan203 FLNK to the calc and calcout records?   FLNK processing would not be done until the $(MUX)VOLT:Chan203 record had actually received the result of the MEAS:VOLT:DC? query so the calc and calcout records would have up-to-date values.
> 
> On Sep 13, 2010, at 2:56 PM, [email protected] wrote:
> 
>> 
>> 
>> Hey everyone, 
>> 
>> I'm having a problem with a calcout record that seems to process before it has passed control to its input record(s). I have a database with two records, 
>> 
>> record(calc, "Current:Coil") {
>> field(DESC, "Coil Current")
>> field(SCAN, "Passive")
>> field(MDEL, ".1")
>> field(ADEL, ".1")
>> field(INPA, "Current:Coil.VAL  NPP")
>> field(INPB, "$(MUX)VOLT:Chan203.VAL  PP MS")
>> field(CALC, "A + B")
>> field(PINI, "NO")
>> field(EGU, "A")	
>> field(SDIS, "0")
>> }
>> 
>> record(calcout, "Voltage:Output") {
>> field(DESC, "Output Voltage")
>> field(SCAN, "Passive")
>> field(INPA, "Current:Coil.VAL  PP MS")
>> field(OOPT, "Every Time")
>> field(DOPT, "Use CALC")
>> field(CALC, "A")
>> field(OUT, "$(VLTPROG)P25V.VAL PP MS")
>> field(PINI, "YES")
>> field(EGU, "V")	
>> field(SDIS, "0")
>> 
>> }
>> 
>> and when I start my ioc, I get: 
>> 
>> Starting iocInit
>> ############################################################################
>> ## EPICS R3.14.11 $R3-14-11$ $2009/08/28 18:47:36$
>> ## EPICS Base built Sep  2 2010
>> ############################################################################
>> 2010/09/13 14:37:11.593 172.25.100.69:1234 write 32
>> MEAS:VOLT:DC? (@203)\n++read eoi\n
>> 2010/09/13 14:37:11.593 172.25.100.97:1234 write 25
>> APPL P25V, 0.000000, 0.1\n
>> 
>> iocRun: All initialization complete
>> ## Start any sequence programs
>> #seq sncxxx,"user=andrewwagnerHost"
>> 
>> epics> 2010/09/13 14:37:11.870 172.25.100.69:1234 read 16
>> +8.92303000E-04\n
>> 
>> 
>> It seems the calcout record processes at init (as desired) passes control to input A which issues the MEAS:VOLT:DC? command but doesn't wait for input A to actually return a value. Input A returns control to the calcout record too quickly so if I print the record I get: 
>> 
>> epics> dbpr Voltage:Output
>> A: 0                ASG:                B: 0                C: 0                
>> CALC: A             D: 0                DESC: Output Voltage                    
>> DISA: 0             DISP: 0             DISV: 1             DLYA: 0             
>> E: 0                F: 0                G: 0                H: 0                
>> I: 0                J: 0                K: 0                L: 0                
>> NAME: Voltage:Output                    OCAL: 0             OEVT: 0             
>> OVAL: 0             POVL: 0             PVAL: 0             SEVR: INVALID       
>> STAT: LINK          TPRO: 0             VAL: 0              
>> 
>> 
>> with an INVALID LINK. How can I guarantee that control from the input is not passed back to the calcout record until it has finished measuring the voltage? Should I set SDIS "Current:Coil.PACT" ? Thanks very much for your help. 
>> 
>> Andrew
>> 
>> 
>> 
> 
> -- 
> Eric Norum
> [email protected]
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System