1771-SDN Devicenet .. no errors but no data!

Searched the forums , but didn't see anything remotely similiar so here goes:

I've got a 2 node DeviceNet setup. One is the 1771-SDN on the PLC5 chassis. The other is a Toyopuc DeviceNet card on its chassis.
The Toyopoc DNet card is set as Master, and polls the 1771-SDN for 122bytes read and write. The 1771-SDN is set up as Slave Mode and polled for 122/122. I then setup the BTW/BTR in the PLC5 for 62word block xfer.

I set the channel to Run and the status word indicates that everything is running perfect. All lights on both units are green, no flashing. But when I try to send test data back and forth, nothing.

Now, that in itself is strange, but I've got this system duplicated elsewhere and its working perfectly.

I don't know a lot about DeviceNet network troubleshooting... what should I be looking for as possible problems? At this point I can't pinpoint whether its a card issue or a wiring issue.

Cheers,
- Dave

62words<>122bytes

node id#s?

The 122bytes = 61 words is the data communication between the two devices. The extra word, 2 bytes, is consumed by the 1771-SDNs special status word on each of read and write. The 1771-SDN is Node 02 and the Toyopuc is Node 00. That part seems to be identical to the other setups I have.

Are there rules to what order devices have to be powered up on a DeviceNet network, or the power on the network itself?

I thought the 1771 SDN had to be the master. I haven't set up a 5 system. I think this was one of the gotchas with them.

Did you set up the SDN as a slave? I didn't now if you could.

I have the 1771-SDN/C .. first model to support being the slave. I set it up in slave mode with the 122/122 polled data setting. When you do that the Input and Output tabs allow you to select that data to AutoMap into data tables. Actually, its also identical to how I configured a Control Logix devicenet card as a slave to connect to a Toyopuc on another system.

Just throwing this out as something to check.

Check the module status register and make sure the module is not in idle mode, bits zero and one, I think. It helps to have the module installation or user guide handy for this.

If it turns out this is your issue, it's a simple matter to toggle the bit in the module command register to set things right.

So, is it safe to assume you were able to configure it as a slave using RSNetworx for devicenet?

What about the dipswitch settings... Do they all check out correct?

Doug-P -- I re-checked my write status register and confirmed the Enable bit was on. The read status confirmed that it was on and that the channel had no faults or stoppages. No luck there

OkiePC -- Yes, RSNetworx was used to configure the devicenet for slave mode operation and dipswitch settings show Channel 2 and 500kbps.

If it were me, I'd connect up with the DeviceNet Traffic Analyzer and capture the I/O data in transit between the Toyopuc and the 1771-SDN. Sometimes capturing the data on the wire is the only way to be certain that the connection contains the data you think it should contain.

If you unplug the 1771-SDN, what reaction does the Toyopuc controller have ?

Are the BTR/BTW instructions executing continuously ?

Well today was a very strange day. I connected the 1784-U2DN into the network again and it gave me a Network Status Indicator flashing green light and when I tried to scan the network it would see the devices but couldn't connect to them and upload. However, the 1771-SDN and Toyopuc were showing Green lights... so on a whim I tried the connection again. For some strange reason the data communication was working!

I have absolutely no clue how to explain this.