We have requested equipment group to consider Ethernet
connectivity since 15 years ago, because of lack of our
manpower. 10 years ago the number of PLCs exceeded 120, and
now 180 for 600m KEK Linac. Some of them strictly required
robustness of PLCs, but many other mainly require remote I/O
capabilities. Most of them were from Yokogawa, mainly because
only Yokogawa had provided program download capability over
Ethernet. They were relatively reliable. That was a period
of "Everywhere TCP".
CAMAC crates, GPIB instruments, temperature sensors, etc.
were connected over TCP, and some others were connected thru
Lantronix XPort. "Everywhere TCP" was remote I/O over
Nowadays at KEKB, we move further to "Everywhere EPICS-IOC".
We started to embed IOCs on to controllers. If we have to
think about failure recovery, etc for remote I/O, why we don't
just use Channel Access. If we use IOC, we can use database
links, sequencer, as well as CA.
As we asked Yokogawa to provide Linux CPU on PLC, we started
to embed IOCs on to Yokogawa PLCs. That eliminates the code
managements at two places of PLC and IOC. We don't need
ladder program conversion to XML. It is a kind of "Poorman's
VME", instead of PLC.
While we keep many VMEs, we are using/evaluating
IOC on PLCs
IOC on Windows on oscilloscopes
IOC on FPGAs
IOC on microTCA/AMC (on FPGA)
I admit that some of them are not cheap, but the balance
between resources justify them.
We are now studying the balance to configuration management
of the infrastructure like name servers, gateways, etc.
>>> On Wed, 16 Dec 2009 12:44:54 JST, <email@example.com> wrote;
> At Diamond we are considering what to use for the next generation of
> discrete I/O. Currently we have a lot of VME based hardware, but we are
> considering a good architecture for a Linux world.
> The model that we are considering is a soft IOC on a Linux system
> communicating over Ethernet using an open, industry standard protocol to
> distributed DIN-Rail mounted I/O points. These I/O points take in
> Ethernet and are powered from a 24V bus that will run around the
> hardware area.
> This eliminates any dependence on a specialized bus architecture (apart
> from Ethernet) on the Linux system, so they can be commodity PC's, and
> hopefully allows us to use widely available, cheap, industrial modules
> for I/O. It will not completely replace all of the requirements
> currently serviced by VME, but would be able to satisfy most of them,
> with the remaining few being serviced by the occasional VME system (or
> FPGA, or some other bus, or something else entirely in the future...).
> This email is to poll the EPICS community as to the experience people
> have had, and recommendations for and against.
> The sort of thing we have identified are:
> 1. Modbus/TCP based modules, such as the Acromag Busworks series
> 2. EtherCAT base modules, such as those from Beckhoff:
> 3. Standard PLC systems where (as distinct from the other two), you
> take Ethernet to a PLC controller which then has a series of modules it
> talks to in a variety of possible ways.
> So, is anyone willing to share their experiences with these or similar
> Nick Rees
> Principal Software Engineer Phone: +44 (0)1235-778430
> Diamond Light Source Fax: +44 (0)1235-446713
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Kazuro FURUKAWA <firstname.lastname@example.org>
Linac&KEKB, High Energy Accelerator Research Organization (KEK), Japan
Telephone: +81-29-864-5200 x4316, Facsimile: +81-29-864-0321
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