Re: Modbus write register update when locally modified

[haquin <haquin@ganil.fr>]

Hi Mark,

Thanks for your solution,
we just removed : field(PINI, "YES"), field(VAL, "1") from the MyParam record to have it initialized with the RBV.

Best regards

Le 19/08/2013 17:21, Mark Rivers a écrit :
> This is a common problem when a device setting can be modified in more than one way.  It could be through some other application, local console as in your case, etc.
>
> Let's assume that you currently have a longout record (MyParam) that has SCAN=Passive, and a longin record (MyParam_RBV) reading that Modbus value that has SCAN=I/O Intr.
>
> Here is a solution.  You need to change MyParam to be soft device support, and add a new record MyParam_write that actually writes the value to Modbus.  You need to add a new record MyParam_sync that copies MyParam_RBV to MyParam.  This will update your longout whenever the longin changes:
>
> record(longout, "$(P)$(R)MyParam")
> {
>      field(PINI, "YES")
>      field(OUT, "$(P)$(R)MyParam_write PP")
>      field(VAL, "1")
> }
>
> record(longout, "$(P)$(R)MyParam_write")
> {
>      field(SDIS, "$(P)$(R)MyParam_Sync.PACT")
>      field(DISV, "1")
>      field(DTYP, "asynInt32")
>      field(OUT, "@asyn($(PORT),$(ADDR),$(TIMEOUT))FILE_NUMBER")
> }
>
> record(longin, "$(P)$(R)MyParam_RBV")
> {
>      field(DTYP, "asynInt32")
>      field(INP,  "@asyn($(PORT),$(ADDR),$(TIMEOUT))FILE_NUMBER")
>      field(SCAN, "I/O Intr")
>      field(FLNK, "$(P)$(R)MyParam_Sync")
> }
>
> record(longout, "$(P)$(R)MyParam_Sync")
> {
>      field(DOL,  "$(P)$(R)MyParam_RBV NPP")
>      field(OMSL, "closed_loop")
>      field(OUT,  "$(P)$(R)MyParam PP")
> }
>
> This is the only way I know how to do it currently, and if you have many records that can be locally changed you need to do this for all of them.
>
> Mark
>
>
>
> -----Original Message-----
> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of haquin
> Sent: Monday, August 19, 2013 9:35 AM
> To: tech-talk
> Subject: Modbus write register update when locally modified
>
> Hi all,
>
> I use Asyn (v4.19) ModbusTCP (v2.4) driver with longout record to write a consign.
> when the plc is switched to Local control mode and consign is locally modified, when the plc is back in remote control
> mode, the record  hosting the consign is not updated with the new current value.
>
> I've checked that the Modbus table is actually updated.
> Is it possible to have the record updated in such circumstance ?
> Such Local/Distant transition doesn't fall into the Disconnect/Reconnect scope.

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