SLC 5/0X rack expansion.

Pete_S

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Join Date
Mar 2015
Location
Portland Maine
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Hi. I am trying to reproduce a customer issue with a multi rack SLC configuration. I have multiple SLC racks (2 4 slot racks with 1746-P2 power supplies, 3 io modules per rack and a 5/04 and a 5/05 cpu respectively). So if my understanding is correct I would just need an expansion cable to connect the racks? Is this correct, or am I missing something?
 
you can connect the racks several ways.

1. rack connection cables.
2.dh+
3. remote I/o
devicenet, control net???

what does the customer have?
exact rack details.

do you have his program?
if yes, look at the configuration.
can you get the program?

what is his issue? maybe someone here has had the same issue.

james
 
I thought the rack connection cable was for expanding the number of I/O slots only.

Not for connecting 2 rack with different CPU

Someone correct me if I am wrong.
 
Correct. The cable connects the "backplanes" of two chassis to expand the number of slots. It essentially treats the two chassis as one big chassis. It cannot be used to connect controllers in two separate chassis.

With two 4-slot chassis you would have slot 0-3 in the first chassis and slots 4-7 in the second chassis. A controller can only reside in slot #0 so you cannot have a CPU in the second chassis.

The SLC 5/04 has DH+ and a serial port while the 5/05 has Ethernet and a serial port. There isn't a real easy way to connect those two. However, there is an adapter that can use the serial port of the 5/04 to connect it to Ethernet.

OG
 
you can connect the racks several ways.

1. rack connection cables.
2.dh+
3. remote I/o
devicenet, control net???

what does the customer have?
exact rack details.

do you have his program?
if yes, look at the configuration.
can you get the program?

what is his issue? maybe someone here has had the same issue.



james

Hi James,

Thanks for the swift reply. I do have the customer project. When I open his .RSS file and go to the I/O configuration I see 2 13 slot racks configured with I/O.

What the customer is reporting is that with our AB Ethernet driver they are able to read tags from I/O points in the first rack, but when they try to add tags referencing I/O in the second rack all tags have bad quality. So I need to use the rack connection method to not introduce additional variables and insure similar addressing. So here is what I have for hardware in front of me

Rack 1 (4 slot with 1746 P2 supply)
SLC 5/04
blank
1746-ib16
1746-ia8

Rack 2 (4 slot with 1746 P2 supply)
SLC 5/05
1746-ia8
1746-ov32
1746-ox8

Is my understanding correct that I could just get the rack expansion cable (p/n currently unknown) and connect these 2 racks and configure as a 2 rack device in RSLogix 500?
 
I thought the rack connection cable was for expanding the number of I/O slots only.

Not for connecting 2 rack with different CPU

Someone correct me if I am wrong.


Sorry for the misunderstanding. I am not trying to connect multiple CPU's in 1 expanded rack. My understanding is this is only possible with Controllogix devices. I was simply stating what I had for hardware at my desk in its current configuration state. I plan to pull the 5/04 and use the 5/05 so I can be connected with RSLogix as I cant use my u2DHP adapter while testing with our drivers as they use the same Virtual COM port.
 
Last edited:
Yes, but remove the cpu from the second chassis. Note too that the expansion cable cannot be very long. Three cables are available.

1746-C7 is 6 inches
1746-C9 is 36 inches
1746-C16 is 50 inches

OG

** edit ** You can change the virtual COM port settings of the U2DHP.
 
you are using the term bad quality.

does this mean they are seeing the bad quality tags in a SCADA system or in the RS500 Program??
 
Yes, but remove the cpu from the second chassis. Note too that the expansion cable cannot be very long. Three cables are available.

1746-C7 is 6 inches
1746-C9 is 36 inches
1746-C16 is 50 inches

OG

** edit ** You can change the virtual COM port settings of the U2DHP.
thank you for for the part numbers, much obliged!

yes I can change the COM port, but we use the same low level drivers as Linx does so I cant have both connections through the u2dhp.
 
you are using the term bad quality.

does this mean they are seeing the bad quality tags in a SCADA system or in the RS500 Program??

bad quality in our DA quick client that we provide for test purposes. all tags are correctly defined on the device in RSLogix 500 with a valid configuration that is in production.
 
very strange... (obviously)
the I/O in the expanded rack should no be different than the I/O in the rack with the CPU.

I assume the the customer's PLC running with no faults???
 
very strange... (obviously)
the I/O in the expanded rack should no be different than the I/O in the rack with the CPU.

I assume the the customer's PLC running with no faults???

the I/O in the rack matches the configuration, according to information provided to me. the process being controlled is a dewatering plant and they are in production so i am inclined to believe this information is correct.

correct he is running with no faults. I am not responsible for the customer project, I am simply trying to create a scaled down analog in my lab so I can determine if there is an issue with our driver when reading tags from I/O cards in Rack 2.
 
Last edited:
there is a program i used only a few time called RSLogix Emulate 500.

This only emulates your SLC program on your PC.

With the SLC500 you a cannot simulate a program in the Processor.
the Processor needs the correct I/O cards physically installed otherwise it will fault.
 

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