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<== Date ==> <== Thread ==>

Subject: Re: Motor Record with Encoder
From: "Brian McAllister" <[email protected]>
To: David Maden <[email protected]>
Cc: [email protected]
Date: Thu, 18 Oct 2001 18:30:48 -0400
>>> On 10/18/2001 at 17:33:12 +0200, David Maden wrote:

  > However, when I boot the ioc, the motor record does not seem to pick up
  > the initial value of the encoder and its DVAL field is zero. I do not
  > seem to be able to restore the DVAL field of the motor at iocInit time
  > via the save_restore mechanism.

I solved exactly this problem today.  Note that this is with version 3.4 of
the motor record, but I'm pretty sure none of the relevant behavior has
changed.

The feature you need to use is the SET/USE mode control.

The procedure is as follows:

    1) put <motor>.SSET 1
       - sets record to SET mode

    2) put <motor>.VAL 1
       - causes .VAL and related fields to be set from
         the readback link value. This also requires the record
	 to be processed, so a DB link must be PP.

    3) put <motor>.SUSE 1
       - sets record to USE mode

This procedure can be automated using a sequence record.  Set PINI=YES so
it gets processed when the database initializes.

It may be necessary to use a delay in the sequence record to guarantee that
the readback value is valid before the motor record uses it.  I used a 10
second delay because the readback PV is on a different IOC (5 seconds
wasn't enough).

----
Brian McAllister                    Controls Programmer/Beam Physicist
[email protected]                        MIT-Bates Linear Accelerator
(617) 253-9537                                           Middleton, MA


References:
Motor Record with Encoder David Maden

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