I hope someone may find what's wrong...

saucekorn69

Member
Join Date
Mar 2005
Location
Quebec
Posts
27
Hi everyone,

I'm writting a PLC's driver following AB DF1's protocol under VB.NET for a ML 1500. It works fine, I thought I had finish, but this error really bug me, I hope someone may have any idea of what's going wrong ..

I can perform "protected typed logical write using three adress fields" as documented in DF1's manuel p7-18 in order to send a value to PLC.
Fact is that driver works great except for the value "16". If I have to send this value (like here, to Output slot 0), PLC denies to accept my packet replying me with a NAK. By making a diagnostic, I can see that It interprets this message as a bad packet, but I cannot understand why.


Here is a copy of a serial monitoring:


Port opened by process "PLC Tester.exe" (PID: 1860)



Request: 2005-08-05 10:56:00 AM.731635064 (+12.9262666000 seconds)



10 02 01 00 0F 00 50 9F AA 02 00 8B 00 00 10 00 ......PŸª..‹....
10 03 BA 42 ..ºB



Answer: 2005-08-05 10:56:00 AM.731635064 (+0.0000000000 seconds)



10 15 ..



Request: 2005-08-05 10:56:05 AM.908149264 (+5.1765142000 seconds)



10 02 01 00 0F 00 E3 B7 AA 02 00 8B 00 00 10 00 ......ã·ª..‹....
10 03 63 44 ..cD



Answer: 2005-08-05 10:56:05 AM.918161864 (+0.0100126000 seconds)



10 15 ..



Request: 2005-08-05 10:56:06 AM.038313064 (+0.1201512000 seconds)



10 02 01 00 0F 00 86 30 AA 02 00 8B 00 00 10 00 ......†0ª..‹....
10 03 3A BB ..:»



Answer: 2005-08-05 10:56:06 AM.048325664 (+0.0100126000 seconds)



10 15 ..



Request: 2005-08-05 10:56:06 AM.138439064 (+0.0901134000 seconds)



10 02 01 00 0F 00 B0 CC AA 02 00 8B 00 00 10 00 ......°Ìª..‹....
10 03 1E CF ...Ï



Answer: 2005-08-05 10:56:06 AM.148451664 (+0.0100126000 seconds)



10 15 ..



Request: 2005-08-05 10:56:06 AM.198514664 (+0.0500630000 seconds)



10 02 01 00 0F 00 07 19 AA 02 00 8B 00 00 10 00 ........ª..‹....
10 03 46 C0 ..FÀ



Port closed


As you can see, every time it failed I retry to send the packet with a
different TNS value, but It still doesn't work.


Does anyone know what should I do in order to make this work ?

Thanks in advance !

Best regards !

Nicolas.
 
The DF1 protocol uses 16 (HEX 10, ASCII DLE) as an idicator for the beginning and end of a message. Notice the 10h, 02h and 10h, 03h combinations at the beginning and end of the message. Your target is interpretting the 10h in the middle of the message as an indication that the message is ending.

The DF1 protocol has a specific mechanism for handling data that matches commands buried in a message. You need to frame the occurracne with a specific character but I don't remember what that character is.

I hope this points you in the right dirtection.

Keith
 
That's what I supposed to, but does anyone know how to make those characters ? Is this documented on AB DF1's manual ??

best regards.

Nicolas.
 
Thank you very much Keith !!!

You guys rock, everytime I've got a problem, someone find out the solution really quickly !! I hope to be good like you are in a couple of years !

I'm glad to be a member of PLCS.NET !!

Best regards.
 

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