issue with PLC on multiple networks

I have an AutomationDirect DL06 PLC (PLC A) that is presently a master on a multi-node RS485/422 network (network 1) using the on-board port 2. I am trying to attach this PLC to a second network (network 2) as a slave using port 2 of a D0-DCM module. Network 2 will not always be active which is why I'd like PLC A to be a slave on network 2.

The problem I am having is when I attempt to start network 2, the red error light on the D0-DCM module flashes along with the green TX/RX lights. And no data appears to transfer between PLC A and PLC B (master) on network 2.

If I rework my programs so the PLC A is the master on both networks, the error light goes out, and communication on network 2 is successful. So I know I have the D0-DCM configured correctly.

What am I doing wrong? Why can't I make PLC A a slave on network 2? It seems to me that I should be able to do this as long as I use a different port for each network.

I'm using DirectNet protocol on both networks. All PLCs are DL06. Each PLC has been assigned unique station numbers, and both ports on PLC A have unique numbers (I've also tried assigning the same number to both ports - port 2 on the on-board and the D0-DCM module - with same results). Both networks are serial. Network 2 will only have two PLCs on it - PLC A and PLC B)

Any help would be appreciated.

Thanks.

Post some of your logic, so we can look at it and assist with troubleshooting. I don't see any reason why you should not be able to do what you are trying to do.

DaleAlanB said:

If I rework my programs so the PLC A is the master on both networks, the error light goes out, and communication on network 2 is successful. So I know I have the D0-DCM configured correctly.

Click to expand...

Right off hand I think this is where the problem is (configuration)

Can you post your configuration?

JBJennings, milldrone, Thanks in advance for your help.

Here is the configuration I'm using. The D0-DCM is in slot 3 of the slave PLC (PLC A in original posting) [third slot from left]. On both PLCs I am using the GX/GY Global (Remote) I/O contacts as my network Input/Output area. I don't use these contacts for anything else.

I have DirectSoft 4 so I have to code the D0-DCM configuration within the program.
Note: The D0-DCM port configuration screens are only in DirectSoft 5.

STR SP0
LD K22E1
OUT V722
LD K4509
OUT V723
LD K55
OUT V727

On first scan:
Per the D0-DCM manual: The above should translate as: Auto Detect Protocol, Hex Mode,
RTS On: 2ms, RTS off 5ms, Base Timeout x 1.5, RS422/485 4-wire/RS232

Station Address 9, 9600 baud, odd parity, 8 data bits, 1 stop bit


Master PLC (PLC B) is using On-Board port 2 configured as follows:
Protocol: Directnet
Base Timeout x 1.5
RTS On: 5ms
RTS off: 2ms
Station: 8
Baud: 9600
Stop bit: 1
Parity: odd
Format: Hex

Master PLC (PLC B) RX/TX code.

STRN SP116
ANDN C700
LD KF209
LD K4
LDA O40000
RX GY220
SET C700

Read 4 bytes from GY220 on slave store at GX0 on master

STRN SP116
AND C700
LD KF209
LD K4
LDA O40200
WX GX400
RST C700

Write 4 bytes from GY0 on master store at GX400 on slave

I would try using V memory values instead of GX and GY, especially if you are using remote I/O. Just a suggestion.

Dale,

I cannot find anything wrong with the configuration. I'm presuming you have verified that the Vmems contain the values in you wrote in the ladder.