Experimental Physics and
Industrial Control System

"Florian Feldbauer" <[email protected]> · 15 Feb 2013 15:45:11 +0100

Hey Marc,

the TMCM142_SAP in my example below is exactly what you suggest, only to

code a different value.

The motor driver needs 3 parameters:

1) Byte 0 is the command number which codes things like "Move to

position" or in the example below "Set axis parameter" (here I'm using

pasynUser->reason).

2) Byte 1 Type/Parameter number. Some commands like "Set Axis Parameter"

use this field to determine

 which axis parameter to read/write. In my opinion this is also a

good candidate for the addr parameter.

3) Motor/Bank number. Axis related commands use this to distinguish

between multiple axes, but our device

    doesn't support this.

 From the hard- and firmware of the TMCM142 this parameter is

currently only used by 2 commands,

 Set/Get global parameter, and only to access "user defined" global

parameters.

Of course one could use the addr to code the 3rd parameter and use

reason to code command and parameter numbers, but then you would end up

with something around 500 strings or so...

Or is there any other way to pass a third paramter from the IOC to an

asynPortDriver?

I also thought about using the timeout, but that would be too confusing

for others to use...

Best regards,
Florian

Am 15.02.2013 15:25, schrieb Mark Rivers:

Hi Florian,

In general I would recommend using pasynUser->reason for the "parameter number" and using the addr parameter for the "motor number".  That is more in the spirit of how they are intended to be used, and allows your driver to work with the next version of your motor controller which might support multiple axes.

Your db file would then look like:

record(ao, "$(P)$(R)Velocity) {
   field(DTYP, "asynInt32")
   field(OUT, "($(PORT),$(ADDR))VELOCITY")
}

ADDR is the motor number (0 for the current controller) and VELOCITY is the asynDrvUser parameter.

Your driver would implement the asynDrvUser interface to convert the string "VELOCITY" into the appropriate "parameter number", which it places in pasynUser->reason.

Mark

________________________________________
From: [email protected] [[email protected]] on behalf of Florian Feldbauer [[email protected]]
Sent: Friday, February 15, 2013 3:14 AM
To: EPICS Tech Talk
Subject: AsynInt32 device support and mbbo records

Hey,

I have written an AsynPortDriver for the TMCM142 1 axis stepper
driver/controller
The motor driver is connected via CAN bus and expects a message with 7
bytes of data:
byte 0: command number
byte 1: parameter number (I'm using the addr parameter from the asyn
interface)
byte 2: motor number (only one motor can be connected to the driver so
it is always 0)
byte 3-6: data (32 bit signed int)

For setting the microstep resolution of the motor driver the data has to
be a number between
0 and 11, each coding a different resoultion.
I wanted to use a mbbo record, which looks like this:

record( mbbo, "PANDA:$(subsys):MOTOR:$(SECTOR):SAP:USTEPRESOLUTION" ) {
    field( DTYP, "asynUInt32" )
    field( OUT,  "@asyn($(BUS),27,1)TMCM142_SAP" )

    field( ZRST, "2048 micro steps" )
    field( ONST, "1024 micro steps" )
    field( TWST, "512 micro steps" )
    field( THST, "256 micro steps" )
    field( FRST, "128 micro steps" )
    field( FVST, "64 micro steps" )
    field( SXST, "32 micro steps" )
    field( SVST, "16 micro steps" )
    field( EIST, "8 micro steps" )
    field( NIST, "4 micro steps" )
    field( TEST, "2 micro steps" )
    field( ELST, "1 micro steps" )
}

Unfortunately, the value inside my writeInt32 function from the
asynPortDriver is always 0.
Do I have to set the ZRVL,...,ELVL fields for asynInt32? Or do I need
another asyn interface for
this record?

Best regards,
Florian

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| Dr. Florian Feldbauer                |
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| Helmholtz-Institut Mainz /           |
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System