SLC-5/04 No communication with 1747-ASB

Hi, My name is Dan, I'm new to the forums and I'm having a problem configuring a SLC-5 for a senior design project. I currently have no access to Rockwell's PLC tech support so any help would be greatly appreciated. I've included everything I can think of below, please let me know if there is more information you need.

Chassis 0 (13 Slot)
Slot 0 - 1747-L541
Slot 1 - 1747-SN
Slot 2 - 1746-IA16
Slot 3 - 1746-IA16
Slot 4 - 1746-IA16
Slot 5 - 1746-IA16
Slot 6 - 1746-IA16
Slot 7 - 1746-OW16
Slot 8 - 1746-OW16
Slot 9 -
Slot 10 -
Slot 11 -
Slot 12 -

Chassis 1 (10 Slot)
Slot 0 - 1746-ASB
Slot 1 - 1746-IA16
Slot 2 - 1746-IA16
Slot 3 - 1746-IA16
Slot 4 - 1746-IA16
Slot 5 - 1746-IA16
Slot 6 - 1746-OW16
Slot 7 - 1746-OW16
Slot 8 - 1746-OW16
Slot 9 -
Slot 10 -

I have the 87 Ohm terminating resistors on both side of the RIO connection.

The following are dip switch settings (which I believe are correct)

1746-SN
SW1
0 0

1746-ASB
SW1
0 0 1 0 0 0 1 1
SW2
0 1 0 1 0 0 0 0
SW3
0 1 1 1 1 0 1 1

The I/O configuration for the 1747-SN is as follows
Scanned Input Words- 32
Scanned Output Words - 32
ISR# - 0
M0 Length - 3300
M1 Length - 3300
G File Length - 5

I realize I have this set up so that my logical rack starts at Logical Rack 8 - Group 0 (which i have configured as a Full Rack in RSlogix 500)

I also realize that I have this set up as complimentary mode (we were having trouble getting anything to work in primary mode)

Right now we are getting a flashing red COMM light on the SN module and a noc message on the adapter. As far as I can tell this means I have something connected incorrectly or configured incorrectly.

If you guys could take a look at this and see if you notice anything glaring that would be greatly appreciated. Just a side note, I'm open to any suggestions and any assumptions that I have stated earlier I'm open to re-configuring.

Please help me get this working!

Thank you!

RIO Rack Numbers are always in Octal, so there's no such thing as "Rack 8" on a RIO network.

The 1747-SN can only scan Rack numbers 00, 01, 02, 03. It doesn't matter physically where they are in the daisy-chain wiring, or what type of adapter they are, but they have to be those first four Rack numbers.

Change your 1747-ASB DIP switch settings to the following:

1746-ASB
SW1
1 1 1 1 1 1 1 1
Logical Rack = 00
Starting Quarter = 0

SW2
0 1 0 1 1 1 0 0
Baud Rate 230.4 kb/s
Complementary (Default)
Chassis Size 8 Logical Groups

SW3
0 1 1 1 1 0 1 1
Do Not Hold Last State
Automatically Restart
Restricted Link Response Time (Default)
Not Last Chassis
1-Slot Addressing
Discrete Specialty Modules
Save Keying Mode

Configure the 1747-SN to scan Rack 00 as a Full Rack.

Oh, and by the way, welcome to the Forum !

Your remote chassis is going to be addressed as follows in the I/O table of your SLC controller:

Chassis 1 (10 Slot)
Slot 0 - 1746-ASB
Slot 1 - 1746-IA16 I:1.0
Slot 2 - 1746-IA16 I:1.1
Slot 3 - 1746-IA16 I:1.2
Slot 4 - 1746-IA16 I:1.3
Slot 5 - 1746-IA16 I:1.4
Slot 6 - 1746-OW16 O:1.5
Slot 7 - 1746-OW16 O:1.6
Slot 8 - 1746-OW16 O:1.7
Slot 9 - Not Addressed by this configuration
Slot 10 - Not Addressed by this configuration

If you want to address the last two slots, they'll be considered Rack 01, a 1/4 Rack and will be I:1.8 and I:1.9 (or O:1.9 and O:1.9 for output data).

The Adapter will also be reconfigured for 10 Groups instead of 8, and you'll turn on the "Last Rack" switch.

Thanks so much Ken, I changed the DIP switch settings to start addressing in Rack 00 and configured it as a full rack and I now have communication.

It took my a while to respond because I've been working on the project but I just wanted to let you know that I appreciate your help.

Thanks =)

Just used your solution - many thanks from England,
Regards,