Experimental Physics and
Industrial Control System

Alain Bertrand <[email protected]> · Fri, 22 Nov 2013 19:21:31 +0100

Hi Christopher,

You should be able to work with floats indeed. However it could be that

I didn't tested it correctly. I will do some trials next week and let

you know. In the mean time, can you please try to grab it as double[]

instead of float[] and see if it works?

Sincerely,

Alain Bertrand

On 11/22/2013 4:10 PM, Christopher J. Pendleton wrote:

Hello. Let me start by saying that I started using EPICS to interface to our
company's devices (http://ptcusa.com/) earlier this year and it has been a
pleasure to work with. You guys are doing great work and I hope I can
contribute to the cause.

One of my colleagues is a big fan of C#, so I pointed him to the EpicsSharp
library. I started using it to help him sort through some issues he was
having. The major one I am seeing is with float arrays (arrays in general?)
while using the MonitorChanged event.

Details:

I have a channel access server running, serving up a float array PV. Both
Python (PyEpics) and LabVIEW (CA Lab) client interfaces see this PV and
recognize it as a float array. No problems here. When I use EpicsSharp, I
can get the float array by using the synchronous call Get<float[]>() on the
channel object. Also no problems here. I see unexpected behavior when I use
the MonitorChanged event. My code:

///
     static class Program
     {
         [STAThread]
         static void Main()
         {
             EpicsClient client = new EpicsClient();
             EpicsChannel<float[]> record =
client.CreateChannel<float[]>("r_I128_channels_test");
             record.MonitorChanged += new
EpicsDelegate<float[]>(record_MonitorChanged);
             Console.ReadKey();
         }

         static void record_MonitorChanged(EpicsChannel<float[]> sender,
float[] newValue)
         {
             Console.WriteLine("Help!");
         }
     }
///

I would expect to see an event fire into my handler, but I don't. What I do
see is an exception in my console window:

///
System.Collections.Generic.KeyNotFoundException: The given key was not
present i
n the dictionary.
    at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
    at PSI.EpicsClient2.EpicsChannel`1.<Disconnect>b__3(EpicsChannel action)
in D
:\Projects\epicsC#\client\EpicsGenericChannel.cs:line 99
///

I dug into the client library code and found that the exception was
happening in EpicsGenericChannel.cs, line 99.

//
p.DataType = (ushort) TypeHandling.Lookup[typeof (TType)];
//

typeof (TType) evaluates to Single[], which isn't in TypeHandling
Dictionary, so an exception is thrown.

Do you expect this behavior? Is there a problem in my client program code? I
found another example on techtalk by Alain Bertrand
(http://www.aps.anl.gov/epics/tech-talk/2011/msg01584.php) that shows almost
the same code with an int[], so I am a little lost. Thanks in advance for
your help!

Regards,
Chris

Christopher J. Pendleton
Director, Software Development
Pyramid Technical Consultants, Inc.
Office: +1 781-402-1700 x114
Cell: +1 781-249-3031

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System