Experimental Physics and
Industrial Control System

"Florian Feldbauer" <[email protected]> · 21 Nov 2013 11:04:44 +0100

Hey Dirk,

we want to control some turbo drag pumps from Pfeiffer Vacuum with EPICS.

The pumps have a RS485 interface, so we can use StreamDevice and asyn

for the

communication.
The protocol from Pfeiffer looks like this (using ASCII symbols):
3 digit address
2 digit action (read "00" or write "10")
3 digit parameter number
2 digit data length
x digits data (according to data length)
3 digit checksum
CR

The checksum is the sum of all ASCII symbols up to preceding checksum

modulo 256 (decimal)

converted into ASCII string.
As an example, reading the actual rotation speed for address 123 would be:
"1230030902=?112\r"

Would it be possible to add a corresponding pseudo-converter to

StreamDevice with little effort,

or would it be easier to use records for the calculation?
In principal we need something like %<sum8> but formatted like %d

Best regards,
Florian

--
----------------------------------------
| Dr. Florian Feldbauer                |
|                                      |
| Helmholtz-Institut Mainz /           |
| Johannes Gutenberg-Universität Mainz |
| Johann-Joachim-Becher-Weg 36         |
| D-55128 Mainz                        |
|                                      |
| Office: SB1 / 00-321                 |
| Phone:  (+49)6131 / 39-29605         |
----------------------------------------

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System