Experimental Physics and
Industrial Control System

John Sinclair <[email protected]> · Tue, 25 Sep 2007 10:44:47 -0400

Hi Zen,
I dread the day I ever created the message box monitor. I was in the
process of converting

our control system to EPICS and was still thinking in the mindset of the
previous tool. I created

the message box widget for a specific application that used it to keep a
running log of events

using a single edm process. The problem is that EPICS does not guarantee
the delivery of every

message, instead it guarantees that the last message received
corresponds to the most recent

write (which is, of course, the precise behavior you want for device
control when the network

is clogged or cpus are being strained).
If you do want to use the message box anyway, notice that the online
documentation, which

is admittedly somewhat terse, says "Data written to a string PV...". So,
the intent of the widget

is to log string pv data. In that EPICS allows all pvs to be considered
a "string", other types

will work but will never include a linefeed character. To force a
linefeed, the string must contain

"\n", e.g. "this is a test\n".
John Sinclair
Szalata, Zenon M. wrote:

I am learning how to use EDM. I have created a message box monitor and connected it to a PV of type double. The soft IOC updates the PV value avery few seconds. A typical value is 9.1990930. In the message box I see 99999999... Where another 9 is appended to the first line each time the PV updates. In the message box properties there is nothing that controls formatting displayed values, nor is there a way to add a newline after each update. Are these somehow controlled via the IOC record setup? What do I need to do to have each full floating point value appear on a separate line? The same string of 9's appears in the log file.
Also, how can I force a "Passive" record processing in the IOC from edm?
Thanks,
Zen

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System