Experimental Physics and
Industrial Control System

Florian Feldbauer <[email protected]> · Thu, 12 Aug 2010 14:10:00 +0200 (CEST)

Hi Dirk,
your guess is correct. The USBCAN maps as /dev/tty on our system.
At the moment I read out my device every 10 seconds.

That means every 10 seconds a bunch of 64 messages are send from the
device.

Within such a bunch every 276 us one message is send.
Florian
On Thu, 12 Aug 2010, Dirk Zimoch wrote:
Hi Florian,
I have to set up a test system to find out what's wrong. That might take a
while. I guess your USBCAN mapps to a /dev/tty... on your system (like a
standard sreial device?).
At which rate do you get these messages?
Dirk
Florian Feldbauer wrote:

 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

> >
>

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| Florian Feldbauer                 |
| Ph.D. student                     |
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System