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

Subject: RE: Sorenson SGA DC power supplies
From: Mark Rivers <[email protected]>
To: "'[email protected]'" <[email protected]>, "[email protected]" <[email protected]>
Date: Thu, 4 Dec 2014 16:46:45 +0000

 

> The first option would be far simpler to set up, but communication with the supply occasionally fails and things have to be reset to restore it

> (I believe simply resetting the Ethernet/Serial convertor usually takes care of the problem).

 

That sounds like a problem with the Ethernet/Serial converter.  Is it a Moxa?  If so, recent tech-talk messages indicated that a firmware upgrade solved the problems on at least one model/version.

 

Mark

 

 

From: [email protected] [mailto:[email protected]] On Behalf Of Mark Davis
Sent: Thursday, December 04, 2014 8:42 AM
To: [email protected]
Subject: Re: Sorenson SGA DC power supplies

 

Hi Linda,

We have 2 different approaches for talking to Sorensen SGA supplies:

- An EPICS record that communicates with the supply using an Ethernet/Serial converter.  This uses a library for managing socket-based communications with various devices.  Both the library and the record where written by John Priller.

- A "Reversing Switch" embedded controller of in-house design that includes an application that runs on DEBROS (a small Linux-like RTOS I wrote that currently runs on Rabbit 2000 and Rabbit 3000 processors).  The controller has its own EPICS record and uses an openModBus/TCP interface (also developed in-house) to communicate with the controller.  NOTE that the controller also supports EPICS CA connections, but doesn't have the horsepower to support more than a few simultaneous clients, so it still requires separate records on an IOC for anything but diagnostics.  I wrote the controller and record code, while John wrote the Modbus interface.


The first option would be far simpler to set up, but communication with the supply occasionally fails and things have to be reset to restore it (I believe simply resetting the Ethernet/Serial convertor usually takes care of the problem).  The second option requires far more effort to set up, but is more reliable and includes a significant amount of logic designed to streamline the communication with the supply as much as possible when using a serial connection (e.g. minimizing the delays inherent in trying to do everything via a serial connection).  It also supports other supply types (such as the DCS seriies).

NOTE:  The only SGA supply I have much experience with is the SGA60/417, and it was indeed a challenge to deal with its limitations.  In addition to the inherent limits in using a relatively low-speed serial connection (19200 baud, in this case), the firmware in the supply itself has some quirks (examples: read-back values often lag significantly behind the actual state of the supply, and there is no way to ABORT an active RAMP command without causing the supply to jump IMMEDIATELY to the value it was ramping toward but had not yet reached).  The DCS series appears to have much better firmware.

A third option you might want to consider is to take the application-specific code I wrote for the embedded controller and use it to create your own asynPortDriver module.   That way you get all the logic needed to deal with the quirks and limitations of the SGA serial interface without the need for any specialized communication interfaces.


If you are interested in any of this, just let me know and I will be happy to forward the relevant code for you to look at.

Mark Davis
Control Systems Software Engineer
NSCL/FRIB
[email protected]



On 11/27/2014 10:35 AM, [email protected] wrote:

Does anyone have EPICS support for the Sorenson SGA series of DC power supplies?

We prefer RS232 streams, but any info useful.

 

Thanks,

 

Linda

 

Software Systems Engineer

Controls Department

[email protected]

+44 (0)1235 778058

www.diamond.ac.uk

Diamond Light Source Ltd

 

 

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References:
Sorenson SGA DC power supplies Linda.Pratt
Re: Sorenson SGA DC power supplies Mark Davis

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