ASCII Communications

[Mtech]

I'm looking to use some keyence LJ-G200 sensors with a Compact Logix L32,coupled with a 1769-ASCII card. Two sensor devices will be used making me need to ports. I am new to the use of ASCII format. I am starting to collect pdf's and sample codes to learn how data is sent and received. I havent purchased anything yet so I dont have a sensor play with so I figured I would research as much as I can. Is there any ASCII guru's out there that can pass on some pointers? It looks like RS5000 provides some decent samples under v15 but things still look Greek to me. Thanks in advance.

 

[ndzied1]

This may be overkill for what you want to do but if you know C programming I would recommend getting The C Programmer's Guide to Serial Communications. Besides the programming part, it has a lot of technical information very helpful in understanding these systems.

http://www.amazon.com/C-Programmers...2?s=books&ie=UTF8&qid=1335410909&sr=1-2-fkmr0

 

[Mtech]

Thank you for the suggestion. I will keep it mind as read through all my information.

 

[Mtech]

Stuck

I am stuck on trying to send the ascii commands to the keyence device (Lj-G5001). I changed my setup to reflect a 1769-generic module,(from a 1769-ASCII) and found a sample code to use for this setup. Once I done this I was able to receive auto commands from the keyence device. I am only wanting to send switch program commands. In the String Browser I am entering my command as PW00CR. But all that is returned is ER,ER,88. If someone gets a few minutes could you please take a look at the attached program to see what I am doing wrong? Thanks in advance.

 

[harryting]

First, you do not need to use generic module, the module profile does exist for 1769-ASCII unders speciality module.

2nd, when dealing with ASCII, it's best to not jump in programming the PLC. Start with Hyperterminal or other terminal program and get the ASCII sequence right, THEN, figure out how to have the PLC do what you just done on the terminal program.

Also, there are other 1769-ASCII post here, I would read up on those:

http://www.plctalk.net/qanda/showthread.php?t=20065

 

[Mtech]

I will read this and will try out hyperterminal as well. Thank you for your feedback.

 

[markdobtech]

Your life will be a lot easier if you make a breakout cable and place a pc in the middle to monitor the comm data on TX and RX. You can easily make a breakout cable. Check out the diagram and description at the bottom of this link: http://airborn.com.au/serial/rs232.html

Use resident hyperterm on the pc as the comm monitor.


We do a lot of work with ASCII comm and PLCS. The ability to see the actual data throughput is the easiest way to figure out what is/is not timed properly. To easily make the cable, l-com.com offers a screw terminal based db9 part no:dgb9ft and gender changers dgb9m. Order (3) 9gb9ft and (2) dgb9m to create all the flexibility you will need.

 

[Mtech]

I am considering using a 435NBX gateway. I hear this could make life easier as well. Have you ever used on of these units? Thanks.

 

[Mtech]

IT dept. (a.k.a. Those guys) won't allow hyperterminal. I will have to shop around for this one.

 

[harryting]

Mtech, there are ton of similiar Serial to Ethernet/IP device out there. ProSoft, BB, Blackbox, etc all makes those. They are especially useful for serial devices mounted far away from the PLC.

The key, still, is to make the serial device work first with your laptop running terminal program.

Yet another option is to find a end device that talks native Ethernet/IP.

 

[Dravik]

IT dept. (a.k.a. Those guys) won't allow hyperterminal. I will have to shop around for this one.

Portmon - http://technet.microsoft.com/en-us/sysinternals/bb896644.aspx
and PuttY - http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html work pretty well together for serial testing.

 

[JeffKiper]

Mtech where are you in Indiana?

 

[JeffKiper]

I have a 435 sitting on the shelf. Nice n easy setup.

 

[Mtech]

I don't want to rule out the 435, so hold that thought. I was thinking of scrapping the ASCII thing altogether. Not that I'm giving up because I'm still planning to get to the bottom of this. But for sakes of future troubleshooting I could hard wire 4 ouputs to code the 16 different switch program. This should keep things simple. The GO signal is just a NPN signal to the plc. I believe this makes things easier for me and our electricians. Now the ASCII delimiter, I'm not sure if I'm entering that correctly... I will read the links on this post tonight. Thank-you