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1769-ASCII

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I'm using a 1769-ASCII and need help with one part of it.  I have no issues with sending data.  The manufacturer shows the following as the process...

 

ascii_process.PNG

My question is: how do I evaluate the XON\XOFF?  The machine states "This communication protocol tells the status if it can receive any data or not to the host by sending "XON" (HEX 11H) or
"XOFF" (HEX 13H) to the signal line."  I never receive any data so I'm not sure what's wrong or if what I'm doing is correct.  The attached file is same code downloaded from AB's website which is what I based my code off of.

 

http://search.rockwellautomation.com/search?client=samplecode&oe=UTF-8&ie=UTF-8&output=xml_no_dtd&proxystylesheet=samplecode&site=sample_code&getfields=*&lang=en&hl=en&sort=date:D:L:d1&wc=200&wc_mc=1&ud=1&filter=0&q=ASCII

 

62119.exe

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The description is a little difficult to read, I agree.

XON/XOFF is basically a software based handshaking scheme, rather than using the RTS/CTS or DSR/DTR handshaking signal pins.   Instead of asserting a "Clear to Send" pin, the printer sends a periodic XON (0x11) byte, then sends an XOFF (0x13) byte to say "I've received my data and am not going to listen again for a bit while I do my printing thing".

I agree that the printer should be sending XON bytes every half-second after it turns on, then it will send and XOFF byte once it's received a command and is ready to process it.

But I don't think the 1769-ASCII supports automatic XON and XOFF handshaking.   There's no mention of it in the user manual.

How do you have the Start Delimiter and Stop Delimiter set up for receiving data on the 1769-ASCII ?

You might try setting up the 1769-ASCII so that XOFF is the Start delimiter and XON is the Stop delimiter.

That's logically backwards, but what it would do is give you an increment on the incoming data Record ID each time that XON arrived, which would tell you that the printer is ready to receive a print command.

I don't know how the 1769-ASCII would behave if it gets End Delimiter values without getting Start delimiter values first.   You should be able to experiment to find out.

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On 2/16/2017 at 8:09 PM, Ken Roach said:

The description is a little difficult to read, I agree.

XON/XOFF is basically a software based handshaking scheme, rather than using the RTS/CTS or DSR/DTR handshaking signal pins.   Instead of asserting a "Clear to Send" pin, the printer sends a periodic XON (0x11) byte, then sends an XOFF (0x13) byte to say "I've received my data and am not going to listen again for a bit while I do my printing thing".

I agree that the printer should be sending XON bytes every half-second after it turns on, then it will send and XOFF byte once it's received a command and is ready to process it.

But I don't think the 1769-ASCII supports automatic XON and XOFF handshaking.   There's no mention of it in the user manual.

How do you have the Start Delimiter and Stop Delimiter set up for receiving data on the 1769-ASCII ?

You might try setting up the 1769-ASCII so that XOFF is the Start delimiter and XON is the Stop delimiter.

That's logically backwards, but what it would do is give you an increment on the incoming data Record ID each time that XON arrived, which would tell you that the printer is ready to receive a print command.

I don't know how the 1769-ASCII would behave if it gets End Delimiter values without getting Start delimiter values first.   You should be able to experiment to find out.

Where would I find this byte of information?  When I send the printer data to print in the terminal, it receives it but never sends anything back?  Right now my start\end delim is dec 013, which is CR.  What is the dec equivelant to XON or XOFF?

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They're just listed as "Device Control" bytes in some ASCII charts (like the one above).

XON is hexadecimal 0x11 = decimal 17.

XOFF is hexadecimal 0x13 = decimal 19.

 

 

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