Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Fri, 14 Aug 2009 08:16:22 -0500

Hi Burkhard,

I'm glad to hear it is working for you.  

I remembered what indicated a potential problem with Wago controllers in the NSLS driver.  It appears that the address to read a particular register is different from the address to write that register.  Normally each of my Modbus port drivers only reads or writes, not both.  The exception is output drivers which can be configured to read once at iocInit to allow for a "bumpless" reboot, i.e. the output record value will match the current state of the hardware.  If the  Modbus addresses for write and read are not the same then this will not work.  Have you tested this, i.e. do output records obtain the current values in the Modbus hardware when the IOC boots?

Cheers,
Mark

________________________________

From: Burkhard Kolb [mailto:[email protected]]
Sent: Fri 8/14/2009 7:51 AM
To: Mark Rivers
Subject: Re: uptodate version of modtcp?

Mark Rivers wrote:
> Hi,
>
> I have an EPICS module called "modbus".  It uses asyn, and works on all supported EPICS architectures (Linux, Windows, vxWorks, etc.).  It supports TCP, serial RTU, and serial ASCII.  It has been tested on a variety of Modbus devices, but probably not WAGO.   Are you using a WAGO?  I looked at the NSLS WAGO support when I was writing my package, and I recall that there was something strange about the way WAGO treated addresses.  I didn't have a WAGO to test, so the driver may need a small addition to work on WAGO.
>
> Here is the link:
>
> http://cars.uchicago.edu/software/epics/modbus.html
>
> Mark

Hi Mark,

thanks, it works out of the box also with WAGO. We have a 750-341
controller and several 750-460 (4 ch Pt100) modules. All I had to do
was modifying the startup script and the database.

Best regards,
Burkhard
--
Dr. Burkhard Kolb
HADES and CBM
E-Mail: [email protected]
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System