Send ASCII characters Via 1734-232ASC

Noob_MW

Member
Join Date
Feb 2020
Location
Ireland
Posts
25
Hi All,


I am new to this site and I am looking for some help,
I am trying to send ASCII characters to a unit that performs a task via a 1734-232ASC module which is connected to a 1734-AENTR series B Point IO then connected to a CompactLogix L36ERM PLC,
I don't have much experience in sending these as strings to the unit,
I have configured the 1734-232ASC unit as per the manufacturer spec, the typical commands for example would be,
/1ZR which homes the unit,
/1A300R moves the unit to position 300


I have sent these from a desktop serial connection software and it works but now would like to send via the plc


Just looking for some help on how to set up the strings and sent the correct data if you have any info I would be very grateful


Thanks,

Capture1.PNG Capture2.PNG
 
I did a special class for a customer on something like this several years ago - and finally got it to work ... I'll attach the files that I used - and hope that they help get you started ...

good luck with it ...
.
 
When you send the commands from a PC, what software are you using to do that?


it is a software supplied with the unit it just sends the characters and receives the feedback from the unit,
I have created a string in the controller tags just would like to send these commands as string to the unit but just unsure which and how to configure the transmit and receive from the 1734-232ASC unit can post more pics if needed

Comsoftware.PNG
 
Last edited:
This is what I use to trigger an scanner, I guess just change the values to as needed.
For my is SYN,T,CR, in the code is 22,84,13 (trigger scanner)See picture
🤾

Trigger scanner.JPG Read scanner from pdf.JPG
 
Last edited:
Based on the screen shot of your communication software, it appears that the device uses the <ETX> "end-of-text" character (ASCII 03) as the message termination delimiter. In order to deal with a varying length of response from the device, it is advisable to set up the 232ASC module to complete a read operation based on this delimiter.

I tried to directly enter this as $03 in the configuration field (your Capture2.png), but it would not take (that dialog only seems to allow the typical ASCII delimiters). I needed to go to the module configuration data in the Controller Tags to directly enter the value 3 in the appropriate location. Looking at your Capture1.png, this would be:

ENTR:6:C.ReceiveEndDelimiter

With this delimiter, the ENTR:6:I.ReceiveRecordNumber will increment each time you get a response from the device, signalling that you can extract the data from the receive buffer.
 
Last edited:
This is what I use to trigger an scanner, I guess just change the values to as needed.
For my is SYN,T,CR, in the code is 22,84,13 (trigger scanner)See picture
🤾


Hay Raybrito this looks good would you have screen shots of your controller tags also if you have it handy
 
Hi All,

Thanks for all the reply's on this, this is a brilliant forum,

I have been trying a few things on this i can get the 1734-232ASC to transmit but it is like i am not sending the data out correctly, I have attached a lot of screen shots on this hopefully you can point out where i am going wrong, just attached the ladder diagram of how i am trying (miserably)
I have all the commands needed in a command array shown, and also shown the output from the 1734-232ASC card, also shown is the configuration of the card,

if you can have a look and see where i am going wrong please be as descriptive as you can as my PLC skills are in this type of communication new as you all can see,

thanks again

Noob

transmit_data.PNG command_array1.PNG 1734-232ASC_config.PNG 1734-232ASC_config2.PNG 1734-232ASC_output.PNG
 
Thanks for posting those screenshots ! I have some suggestions and thoughts.

1. Add a one-shot as a rung condition with the Foot Pedal. When you set that input high, the ADD instruction that increments the .TransmitRecordNumber will increase every program scan for as long as the Input is high, causing multiple transmissions as fast as the module can go. Even a quick tap on a physical switch usually keeps the Input high for several hundred milliseconds.

2. Find out if your terminal emulator software sends a Carriage Return after each line, or a Carriage Return and a Line Feed.

$R is A-B shorthand for Carriage Return (decimal 13, hexadecimal 0x0D), and $L is A-B shorthand for Line Feed (decimal 10, hexadecimal 0x0A).

But the 232ASC only supports one automatically-appended Termination character on the Transmit side.


I can't guess how your O.Data[0-3] ended up with 0,0,0,$04 in it, when you should have "/1ZR". Check the rest of your logic (or ZIP and post it) to see what else is moving data into that other than CommandArray[0].

That's it to start. If you can provide some additional info about that successful terminal emulation you posted about previously, please do so. I'm particulary interested in whether just CR, or CR+LF are at the end of each ASCII transmission.
 
Hi Ken,

thanks for the info, i have attached my program in the Zip, and a section from the manual regarding the communication in the other two if you can have a look when you have a chance and see what i am doing incorrect,

I will also tryout what you have suggested in the morning, thanks again
 

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