DirectNET on DL-06

[Stan]

Several years ago I wrote a communication driver in LabVIEW to communicate with Directlogic 405 series PLC's using the DirectNET protocol over a serial interface.  I've used the driver with 430, 440 and 450 series PLC's on dozens of applications and it always performed well.  I recently tried to use the driver to communicate with a DL-06 CPU with poor results.  The problem is that for every successful read or write to the PLC I get 10 to 20 "NAK" responses from the PLC.  Is there something different about the DL-06's implementation that I'm not aware of?

[BobO]

There shouldn't be. Different CPUs do have differing sensitivity to timing however. You might try playing with the turn around delays between various segments in the protocol.

[rlp122]

One other thing to note, the DL06 is a lot more sensitive to having all replies that need an ACK to have an ACK.  The DL405 series is a bit more lenient in allowing 'needed' ACK responses to pass without timing out.