How retrieve serial data in the controller using the 1769-ADN and 1769-ASCII modules?

Firstly some background:
I have to add a 1769-ASCII module to an existing plc installation done by another company some years ago.
The 1769-ASCII will be added to the Compaq I/O 1769-ADN DeviceNet Adapter which already has 2 Input and 1 Output modules.

Configuration is as follows:
1769-L32E Controller + 1769-SDN/B DeviceNet Scanner Card + 1769-IQ32/A + 1769-QW16/A
Via DeviceNet To:
1769-ADN/B + 1769-IQ32/A (slot 1) + 1769-IQ32/A (slot 2) + 1769-OW16/A/FW Rev 3.1 (slot 3) + 1769-ASCII (slot 4) + 1769-PA4 + 1769-ECR

I have tried to use manual I/O mapping but could not get it working. Eventually I just used the auto map future. Existing modules mapping stayed the same because I have added the ASCII module to slot 4.

PLC now seems to be happy with the new I/O card.
Barcode scanned with barcode scanner on the 1769-ASCII input appears in the Controller’s Local:1:I.Data[xx] array. So I can see for example the barcode length in part of the 32-bit word and analyzing the rest of the words I can also see the individual characters of the barcode.


Now my question is: What is the correct method to use for extracting all the characters from these 32-bit words to construct the original string scanned?

I have looked on the web for more info using the 1769-ADN and 1769-ASCII modules together, but could not find any. The 1769-ADN User Manual I have describes various I/O modules, but not the 1769-ASCII.

Thanks,
Johannes

Here is a link for the user manual for the 1769-ASCII module.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1769-um012_-en-p.pdf

There is a guide for installation and program for the module.

There is some samplecode at Rockwell Sample Code Library.
Link for 1769-ASCII module sample code:

http://samplecode.rockwellautomation.com/intradoc-cgi/nph-idc_cgi.exe?IdcService=GET_SEARCH_RESULTS&QueryText=%28dSecurityGroup+%3CMATCHES%3E+%27Sample_Code%27%29+%3CAND%3E+%28xSC_Title_EN+%3CSUBSTRING%3E+%60ASCII%60%29+%3COR%3E+%28xSC_Description_EN+%3CSUBSTRING%3E+%60ASCII%60%29&DefaultQuery=&urlTemplate=%2Fidc%2Fgroups%2Fpublic%2Fdocuments%2Fwebassets%2Fsc_search_results.hcst&ftx=&SortField=xSC_Title_EN&SortOrder=Asc&SortSpec=&prepopVal=ASCII&passedType=combinedfields_EN&passedParameter=ASCII&submitQueryForm=%C2%BB

Maybe there is an idea or two for your project

Thanks Jera,

I have the manual, but at first thought that it won't be of any use since I am using it through DeviceNet.

Problem now is that with the ascii module's data being auto mapped, the data starts at Local:1:I.Data[4].16 and not Local:1:I.Data[4].0. This is because the data from the 1769-OW16/A/FW Rev 3.1 module is in the first to bytes of Local:1:I.Data[4]. So I must now make a plan to get this offset sorted.

As mentioned before I could not manage the manual mapping to work where I tried to start the ascii module's data from Local:1:I.Data[5]. Then Local:1:I.Data[4].16 to Local:1:I.Data[4].31 would have been unused.

I will give this some thought and maybe try manual I/O mapping again. I obviously must be doing something wrong.

Thanks,
Johannes

You can use a SINT array tag to help shift your ASCII string into a readable format.

Perform a Copy Synchronous (CPS) instruction on the part of the 1769-SDN input data table that contains your string.

CPS
Source Local:1:I.Data[4]
Dest MyCharacterArray[x]
Length xx

The trick is the length: set it to the number of characters in your ASCII string plus 2.

Now the array tag MyCharacterArray will include:

MyCharacterArray[0] = Some byte we'll ignore
MyCharacterArray[1] = Some byte we'll ignore
MyCharacterArray[2] = First character of the ASCII String
MyCharacterArray[3] = Second character of the ASCII String
MyCharacterArray[4] = Third character of the ASCII String

and so on.

Next you're going to move that ASCII data from the SINT[x] array tag into a real String tag.

Use a MOV instruction to place the desired Length into the string tag's .LEN sub-element.

Use a COP instruction to place the MyCharacterArray bytes into the String tag's .DATA array. The .DATA array is an array of 1-byte SINT elements, just like the character array you created above, so the Length is the number of characters in your string.

COP
Source: MyCharacterArray[2]
Dest: MyStringTag.DATA[0]
Length: xx

Thanks Ken,

I only saw your post now.

After a few hours of struggling I have managed to get the scanner to work.

The method I used is almost exactly as your method. Great to know that this is how it is done.

I still am concerned about the fact that I could not manage to manually map the I/O…

Johannes