Experimental Physics and
Industrial Control System

Hi Andrew,

 

> There is one command that I need to send to the instrument occasionally that has a length of around 2000000 chars. 

> Based upon my observations, it takes about 20-30 seconds to send that command through a waveform record and receive a response back through StreamDevice. 

 

We need more information.

 

What is the network interface speed on the device (100 MBit/s, 1 GBit/s, etc.).

 

What is the asyn command you are using to create the asyn port?

 

What does the definition of that waveform record in your database file?

 

What is the Stream protocol you are using to send the waveform record data?

 

> I was wondering if anybody has experienced similar behavior with StreamDevice for very long commands and how to potentially speed it up. 

 

I have used large waveforms with Stream on a few occasions, and I have not seen that Stream was slowing things down.

 

> Should I investigate utilizing asyn or some other drivers, and if so, can it be run in conjunction with StreamDevice? 

 

If you are using Stream then you must already be using asyn as the underlying IP driver. 

 

You should turn on asynTrace to look at the communications with the device, which will include timestamps.

 

asynSetTraceIOMask myPort 0 HEX

asynSetTraceMask myPort 0 DRIVER|ERROR

 

You could easily write a little asyn port driver on top of that driver to send the data.  But that is basically what Stream does, so it is surprising that it is slower than a C socket program. 

 

If the above suggestions don’t offer a hint then you can run the IOC in a profiler like “perf” and see where it is spending its time.

 

Mark