Experimental Physics and
Industrial Control System

Dear Dirk,

The device is custom hardware. The CAN messages come from a AT90CAN64 microcontroller with a PCA82C250 CAN transceiver.
http://www.atmel.com/dyn/resources/prod_documents/doc7679.pdf

This mircocontroller send one message after another.
They all look like "t6804NODDDDCH\r" where NO is the channelnumber (0-63), DDDD the appropriate 14-bit conversion result from the ADC and CH
an 8-bit checksum. All coded in hexadecimal
The baudrate of the CAN bus is set to 1 Mbaud.

Florian

On Tue, 10 Aug 2010, Dirk Zimoch wrote:

Hi Florian,

Looks like a race condition. I have to look in the driver. I fear there is nothing you can do about it.

How does the communication work? You say you get 64 messages in series. What do they look like? All like "t68043F34AAA1\r" (only difference in $(no))? That is the timing of these messages? Do they all come in one burst? Do you have a link to the device documentation?

Dirk

Florian Feldbauer wrote:

Hello all,

I ran into a problem when reading from a serial device using I/O Intr
processing with streamDevice. I receive 64 messages in series and have
one record for each message.
Now and then  I get the error message from epics:

timerQueue INTERNAL ERROR (PANDA:FEMC:PROTO192:THMP:680:CHK:00): timerExpired() unexpected ioAction None

Any idea how to fix this problem?

This is the db:
record (scalcout, "THMP:$(ID):CHK:$(no)")
{
  field (DTYP, "stream")
  field (SCAN, "I/O Intr")
  field (CALC, "((K XOR L) XOR C)==E?(K<<8)+L:LL")
  field (OUT,  "@THMP.proto getMsg($(no)) USBCAN1")
  field (INPC, "$(no)")
  field (INLL, "INV CHK")
}

This is the protocol:
Terminator = CR;
getMsg{
  in "t6804\${2}%(K)2X%(L)2X%(E)2X";
}

This is an example string, which is sent from the device:
t68043F34AAA1\r

Best regards
Florian

Replies:

Re: Problem with streamDevice and I/O Intr Florian Feldbauer

References:

Problem with streamDevice and I/O Intr Florian Feldbauer

Re: Problem with streamDevice and I/O Intr Dirk Zimoch

Re: Problem with streamDevice and I/O Intr Florian Feldbauer

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