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serial read, and data import into spreadsheet

I think it would be best to parse after.  This way you don't have to worry about leaving bits in the buffer and flushing it out.

 

Jon

Applications Engineer
National Instruments
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Message 31 of 86
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Since I haven't done this before in LabVIEW, are there some examples somewhere?

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Message 32 of 86
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Another newbie question: Does an instrument driver need to be installed for a device to properly send a serial message?  I have a couple pieces of equipment that don't have associated instrument drivers - is that a problem?

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Message 33 of 86
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There are literally thousands of instrument drivers available (including the 34401 that comes with LabVIEW) and they all parse the return strings from a VISA Read in some form or another. How they parse is very dependent on the instrument. Attach a typical string returned.

 

Your code right now does not use an instrument driver so of course one is not required.

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Message 34 of 86
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Thanks for the response.  Conceptually, what I want to do is strip out the data from the serial message.  The way a serial message packet is organized is that it has a start bit, 6 data bits, and a start bit.  Would it be best to grab 8 message bits, strip off the first and last, and somehow recover bits 1-6 into an unsigned data packet?

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Message 35 of 86
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Sorry - RS232 serial message packet is: 1 start bit; 7 data bits; 1 parity bit; and 2 stop bits.  So I guess I read 11 bits, strip bits 1-6, and reassemble into data?

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Message 36 of 86
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However, 10-bit N81 is 1 start, 8 data, and 1 stop (no parity).

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Message 37 of 86
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1) Typically, you always want to read out everything the buffer has to offer as opposed to asking for N bytes and hoping you get it.

 

2) Parsing out the data that you want from a data packet is very typical LabVIEW 101. Use one of the many String parsing functions. I almost always use Match Pattern but there are others.

 

I once worked with a data packet that was a few hundered bytes long - and this varied from message to message - and the "data" was only 2 bytes!

 

Richard






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Message 38 of 86
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Thanks...the plot is thickening.  I wasn't aware that companies would deviate from the RS232 protocol to allow unique formatting of their data - very eye-opening.  I'm working on getting some datasheet stuff that explains the frame formatting for the products I'm using.  I found the user guide for the Cooper Instruments & Systems Model BG100 force gauge.  However, I can't find a datasheet or user manual for the Mastech M9803R multimeter (in-house or online).  The BG100 will require a message be sent to it (\?) to release data onto the serial bus.

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Message 39 of 86
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tgilbert wrote:

I wasn't aware that companies would deviate from the RS232 protocol to allow unique formatting of their data


 

RS232 "standard" does not define any character limit, length, order, etc. - you are free to send anything down the pipe you want. RS232 is an electrical standard for the interface.

 

Richard






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Message 40 of 86
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