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,