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
http://www.acromag.com/models.cfm?Product_Function_ID=28&Category_ID=22&;
Group_ID=2
2. EtherCAT base modules, such as those from Beckhoff:
http://www.beckhoff.com/
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
systems,
Cheers,
Nick Rees
Principal Software Engineer Phone: +44 (0)1235-778430
Diamond Light Source Fax: +44 (0)1235-446713
