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<== Date ==> <== Thread ==>
Subject: RE: Stream Device: Parse response that includes checksum of command string
From: "[email protected]" <[email protected]>
To: 'Eric Norum' <[email protected]>, David Vine <[email protected]>
Cc: "[email protected]" <[email protected]>
Date: Fri, 3 Aug 2018 08:56:14 +0000

If you need to preserve and compare the actual TX checksum with the value returned with the received data, how about:

 

a)       Create a calc record to pre-calculate the transmitted command checksum

b)      In the protocol file, read the checksum return value into another record, with a format specifier: %4X  e.g.: IN “#01 15AA %4X\r”

c)       Create a further calc record to compare the calculated with received checksum.

 

But I suppose it comes down to how you ultimately want to handle the comparison.

 

Regards,

Ian

 

From: [email protected] <[email protected]> On Behalf Of Eric Norum
Sent: 03 August 2018 02:20
To: David Vine <[email protected]>
Cc: [email protected]
Subject: Re: Stream Device: Parse response that includes checksum of command string

 

I have no idea how to handle this in StreamDevice, but perhaps you could push an interposed interface on top of the standard ASYN serial or IPPort driver to handle the sequence numbers and checksumming?



On Aug 2, 2018, at 5:44 PM, David Vine <[email protected]> wrote:

 

Hi all,

 

i'm writing device support for the MeCom protocol for a TEC driver from Meerstetter Engineering.

 

In order to parse the response correctly I need to calculate a checksum thats not included in the response. This is because the response includes the checksum of the command and not the response.

 

For example:

 

Command format:

# address sequence_number command CRC16 terminator

# 01 15AA ?IF 257D \r

 

Response is:

# address sequence_number CRC16 terminator

# 01 15AA 257D \r

 

So to parse the response I need to calculate a CRC that's not included in the response. For example:

 

OUT "#0115AA?IF%<xmodem>\r"

IN "#0115AA%<xmodem>\r" but the CRC is for the OUT not the IN.

 

Any ideas would be much appreciated.

 

Thanks,
David

 

— 

Eric Norum

 

 

 

 

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References:
Stream Device: Parse response that includes checksum of command string David Vine
Re: Stream Device: Parse response that includes checksum of command string Eric Norum
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