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| <== Date ==> | <== Thread ==> |
|---|
| Subject: | Re: Asyn getting DTYP field in drvUserCreate() |
| From: | Mark Davis <[email protected]> |
| To: | [email protected], Mark Rivers <[email protected]> |
| Date: | Tue, 20 Mar 2018 07:24:28 -0400 |
HI Mark,We are working on a newer version of an asynPortDriver-based driver that creates the asyn parameters during the call to drvUserCreate() based on the string passed to it, which means that the string must include the asynType for the new parameter. This avoids the need to include the list of parameters as part of the code (requiring a unique version of the driver for each type of device it can talk to).
This works well, but it means a bit of redundancy since the asynType is specified both in the DTYP and the INP/OUT string for the record.
I believe the documentation for the asyn module (and emails from you on this list ) state that the asyn module is designed so that it can be used by clients other than the EPICS record interface, so there is the issue of whether or not it would even be possible to provide this information in a manner that would not depend on what the client is.
Obviously, the question as stated ("What is the DTYP" value in the record?") assumes the call is on behalf of an EPICS record, so the answer is NO. On the other hand, I also assume that, whatever the client is, it has to specify which of the asynType interfaces it is using to communicate with the asyn layer, so the question(s) could be restated as: "Is the asynType known before the call to drvUserCreate(), and if so, could it be make available to the drvUserCreate() function (either as part of the information in the asynUser struct or a function that drvUserCreate() can call)?"
Mark Davis NSCL/FRIB Controls Staff Engineer [email protected]
On 3/19/2018 6:11 PM, Mark Rivers wrote:
Hi Konrad, I can't think of a way for the driver to know the value of DTYP. Of course you specify both the drvUser string and the datatype when you call createParam() so your driver knows the datatype that a particular drvUser string will be using. Why do you need to know the DTYP? Mark-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Konrad, Martin Sent: Monday, March 19, 2018 8:39 AM To: EPICS Tech Talk <[email protected]> Subject: Asyn getting DTYP field in drvUserCreate() Hi, I'm wondering if there is a way I can get access to the DTYP field of the record from asynPortDriver's drvUserCreate method. Once createParam() has been called in drvUserCreate() I can get the type by calling getParamType() but how do I get access to this information in drvUserCreate()? It seems like other drivers are duplicating this information into the INP/OUT field (see e.g. [1]). I'm wondering if there is a more elegant way to do this. Thanks a lot, Martin [1] https://urldefense.proofpoint.com/v2/url?u=http-3A__controls.diamond.ac.uk_downloads_support_aravisGigE_0-2D3-2D&d=DwIFAg&c=nE__W8dFE-shTxStwXtp0A&r=D7ZiziuMQuq40HlGYOZPBg&m=ye8rwKce1N2smS_Qv4NJE7cxkvL2pAyhv01q1CorLNY&s=4dEd2vIEg8lp5k3Z8SyaW9RUE-YJbhcHHYpmwmR0EXg&e= 5dls5/documentation/doxygen/aravisCamera_8cpp_source.html#l00326 -- Martin Konrad High Performance Controls Team Leader Facility for Rare Isotope Beams Michigan State University 640 South Shaw Lane East Lansing, MI 48824-1321, USA Tel. 517-908-7253 Email: [email protected]