Hi Zen,
This is my first post to this tech-talk. I was surprised to see that the Beckhoff hides much of its useful memory.
Have you tried a RIO? I recently used one and the whole array table is read/write via modbus and all operations are done in one modbus packet. I even wrote some embedded code to store some interesting data in the array so I could get at it via the modbus front end. Here's the one I used: http://www.galilmc.com/products/rio-47xxx.php
-Dan
-------- Original Message --------
Hi Mark,
I am still working on an IOC to control stepper motors with Beckhoff
devices (KL2431 and KL2541). I am using your modbus (R2.2) support module.
Beckhoff devices are called bus terminals. A bus terminal has two types
of registers.
One is a small set, typically 2 and in the case of the KL25x1 terminals
3, that one can read from or write to directly. Let's call them
visible. The poll thread in modbus does IO to these registers.
The other type is what I call "internal" or invisible registers. One can
access these registers via the visible registers only. Hence, multiple
operations need to be performed on the visible registers to either read
from or write to an invisible register.
I find that while I am writing to one of the invisible registers, at
times the periodic reading from the visible registers in the poll
thread, interferes with the writing process.
I assume that I can control the poll timeout using your
poll_delay.template record.
So, I am thinking that I need to change the poll timeout for the
terminal I am trying to write to to "disable" poll reading from the
terminal. I use seq records to sequence these read and write operations
and I could add at the beginning of the sequence a request to set the
timeout, to let's say 10 seconds, and at the end of the sequence restore
the original timeout.
Is the thread woken up when a new timeout value is written out to the
modbus module?
Is there a better way to make sure that the poll reads do not interfere
with the reading from and writing to the invisible registers?
Thanks Mark,
Zen
