Re: dm and edm problems with CA gateway

[Ralph Lange <Ralph.Lange@bessy.de>]

Hi Rolf,

we have seen the same problems with the V2.0 Gateway running on Linux. I 
was able to cut it down to a small Linux system with just one analog 
record running on a soft IOC and a Gateway running on the same machine 
exporting this channel on a different port number. Starting camonitor on 
a different host to directly watch the channel on the IOC I was able to 
see random junk values being written into the channel as soon as two 
clients are writing fast (slider) through the Gateway. Not just jumps 
(that I'd expect), but really random bit patterns that are interpreted 
as doubles. No matter which system the clients run on (tested with HP 
and Linux). Connecting the clients directly to the soft IOC - no problem.

At BESSY it didn't kill hardware as our DRVHs are set properly ... I 
hope. We lost the beam a couple of times until - as an instant measure - 
we stopped running write accesses through the Gateway. Read accesses 
seem to work fine.

The V1 Gateway does not show this behaviour - but we had to switch to V2 
because the old hardware died.

I was already reporting this problem some months ago, but the APS 
installation hardly uses write access through the Gateway (if at all), 
so Ken doesn't see these problems - which makes it hard finding the bugs 
as well as the motivation to fix them. But again: One Linux box running 
one ao channel on a soft IOC, the Gateway, the camonitor, and two simple 
clients is enough to reproduce the problem. (On my RH8 Linux box, at least.)

Hope this helps (well, I know it doesn't really, but ...;-)
Ralph


Rolf Keitel wrote:

> **** Has anybody else experienced these problems? ****
>
> When we are operating sliders to write process variables through the 
> CA gateway, every now and then on releasing the sliders the gateway 
> writes huge (and I mean   r e a l l y   huge positive or negative) 
> numbers to the IOC, which set the PV to the upper or lower end of the 
> allowed range.
> This never happens if you don't use the gateway.
>
> We observed this behaviour both with dm and with edm (running on 
> Solaris or Linux Redhat 9).
> The gateway is running on a Linux (Redhat 9) box. Several gateway 
> releases up to Beta18 (built against EPICS R3.14.6) exhibit this 
> behaviour.
>
> We lost a couple of devices, where a user hadn't specified a proper 
> DRVH for the setpoint.
> We have taken the gateway out of operation until this is resolved.
>
> - rolf -