Experimental Physics and
Industrial Control System

bohmm <[email protected]> · Fri, 17 Apr 2015 10:37:40 +0100

Hi Tomáš,
 I didnt specify some important things about the setup, you are right:

I am using Ethernet device attached to a PC where IOC with Stream is

running. The device is set up to trasmit data and the data exchange

speed depends on the frequency of external trigger

I have an EPICS record configured SCAN="I/O Intr", DTYP=stream and that

has only the "in" command defined in the .proto file, as you said.

The amount of data:

 Just doubles (values of power measurement) received at the frequency of

the external trigger (for us no more than 10 Hz).

When in Interrupt mode, the device receives the data automatically at

the frequency of the ext. trigger.

Interrupt mode for this power meter means, that device receives the data

whenever external trigger occurs, on the other hand in polling mode, you

first send a request to the device ("out" .proto) and obtain a response.

(Here I am not sure what yout meant so - Data also can be received

non-periodically in interrupt mode, depends on the nature of ext. triger

signal)

I think this is not the case of fast rate data transfers.

I should also mention, that when doing a telnet to the Gentec directly,

and typing in the command to stop the I/O interrupt mode, everything

works fine.

Peter Owens, the original author of the stream protocol (which otherwise

works perfect) also says he has seen cases where a busy device can't

handle a serial port - but works fine over an Ethernet port, which he

thought is this case.

I hope this helps to clarify

Thanks
Marek

Dne 2015-04-16 13:37, Mazanec Tomáš napsal:

Hi Marek

I'm not sure if I understand your setup correctly, so...

you're using RS232 device attached to a computer where an IOC with
streamDevice is running in order to acquire data from it.
If the device is set to transmit data, it does that at 10Hz rate.
An EPICS record is configured with SCAN="I/O Intr", DTYP=stream....
and reads the data using streamDevice protocol command which has only
"in" command defined.

If so, it should work smoothly.
Of course, it depends on data. What is the amount of data and what
structure it has ?
And then it depends on serial line speed.

Which of the device modes (Polling, Interrupt) sends the data
automatically and periodically at 10Hz ?
Does the interrupt mode means the data are sent in the same way as
poll but non-periodically ?

I've checked S-LINK's product webpage. It mentions some "Fast rate
data transfers to PC" at 10kHz rate. Is this the case ?

I'm interested, we have got one S-LINK in lab too. However its
integration to EPICS may not happen at all.

Thanks,
Tomas Mazanec

________________________________________
Od: [email protected] [[email protected]] za
uživatele bohmm [[email protected]]
Odesláno: 14. dubna 2015 12:07
Komu: Tech talk
Předmět: Gentec S-link power meter problem with ending I/O interrupt
 measurement

Hello,
  I am an EPICS newbie and trying to implement statistics functions for
our energy meter. Our laser system is running at 10 Hz and the energy
meter has to catch every pulse energy/power value for the statistics to
be computed properly. So the energy meter is running with an external
trigger. I am communicating with the device via StreamDevice using
serial commands.

 The device supports two acquisition modes: Polling ("Free running")

and

I/O interrupt (device is generating interrupts).

The problem is, once I get into I/O Interrupt mode @ 10 Hz, the device
is so busy receiving the data, that any other byte streams send to it
via StreamDevice do not get through. The consequences are that I am not

able to send the command to end the I/O Interrupt mode once I started

it

and get back to Polling ("free running"), and also that the devices

does

not receive its other statuses.

At really low repetition rates (@ 0.5 Hz) this problem does not occur,
the device has "time to answer".

Did anybody deal with a similar problem? Is it possible to solve

without

writing a driver?

Best regards

Marek Böhm

--
___________________________________
Ing. Marek Böhm, RP2 Control Engineer

Institute of Physics AS CR, v. v. i.

HiLASE Centre

Za Radnicí 828

252 41 Dolní Břežany

M:    +420 606 259 414

T:    +420 314 007 726

E:      [email protected]

W:    http://www.hilase.cz <http://www.hilase.cz/>

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System