Experimental Physics and
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Greetings, Since there seemed to be no reply to my original post, and I was able to figure this out, I'm posting my solution for the benefit of the community.1) how to dynamically (at run time) generate new PV names based upon the current box (node) the code is running on. This nodeName is comprised of XXX-123456:<PV_NAME>, where the 123456 is the last 3 bytes of the box's MAC address. So Box A would be XXX-123456:<PV_NAME> and box B would be XXX-7890AB:<PV_NAME>, etc. Solution: - During initialization, my init code will generate a file: nodeName - this file contains the following 1 line: epicsEnvSet("EPICS_NODE_NAME", "XXX-123456:") - Each record in the DB is defined in a similar manner: record(longin,"$(nodeID)Sample1_R") - In the st.cmd file, I added the following line: < opt/data/nodeName - This occurs AFTER the ioc_registerRecordDeviceDriver call and before loading of each (of 3) database files - Then, the database records are loaded in this manner: dbLoadRecords("db/Variables.db", "nodeID = $(EPICS_NODE_NAME)") - The end result is as I desired: Each PV is now pre-pended with the unique nodeName generated @ boot time. This took a bit of research and searching around, though the tech-talk mailing list and the documentation. Eventually, I was able to piece together enough so that this solution revealed itself. Thanks! Regards, Stephen Beckwith ========================================================== Original Post:Greetings All, I have the following quandray to which I am unable to find a solution. Given my (limited) understanding of EPICS and how it describes it's databases/records, maybe I'm missing something here, or maybe I'm just SOL. Setup: EPICS 3.14.12.4 ASYN4-22 Target: Host mode run for testing (AMD x86, Ubuntu Linux) Eventual target is Dual-Core ARM Cortex A9 running Embedded Linux. Desired Goal: @ initialization (run-time), when the records are loaded (after initialization), via a .subs file, have the .subs file itself include another file that was written during initialiation which contains data for macro substitution. Current setup: - st.cmd uses dbLoadTemplate "db/node.subs" - node .sub has 3 sets of: file "db/db1.db" { { nodeID = "AA-000102:" } } - This then gives one a Process Variable (PV) of: "AA-000102:SystemTemp" for example This works just fine dandy. Now, what I would like to do is: Replace the "AA-000102" with another string, read from a file that was genrated/written prior to loading the DB. So this becomes like a "macro within a macro" sort of situation. Scouring tech-talk doesn't turn up anything - there a couple close ones, but trying them failed. . . The "AA-000102" is the "node name" for the device where "000102" is really the last 3 bytes of the devices MAC address. I have the code that generates this information, that I can then write to a file, or EXPORT to the environment (though I believe this would be too late to have any affect). The "hard way" is for me to re-create this .subs file @ initialization with the correct information, but that seems alot of work. Or run some utility prior to starting EPICS IOC to generate this static file. . . I was hoping the EPICS system would be smart enough handle this for me. This is a "run-time" binding (sort of), which limits my options over a static setup. Thank you for your time and expertise. Regards, Stephen Beckwith
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ANJ, 17 Dec 2015 |
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