What are my options for expanding a SLC 5/04 system?

[wildswing]

Hey fellas,

I currently have a 1747-L542C SLC 5/04 OS401 Series C in a 10 slot chassis. The chassis is filled with 16 point discrete IO modules. Pic of IO config attached.

We need to expand. Existing IO is only 144 points. Docs say it can handle 4096, so that's not an issue. Am I reading that right?

Unfortunately the existing enclosure, in which the chassis is housed, is also full, so we'll have to add another enclosure nearby. What are my options?

1 - I'm aware of the 1746-C# interconnect cables.
> Do these just connect chassis backplane to chassis backplane or do they take up any chassis space (slots)?
> 4 feet is the max length? We might need to go further than that.
> How are the extended chassis modules addressed? Just like the local ones, just slot numbers goes up by 1, or is there a rack number?
> Does the cable provide power or does the extended rack require a power supply?

2 - I also see that the SLC can support remote IO using a 1747-ASB. Would this take up 1 slot in the existing chassis, or do I use the port on the processor for the scanner and the ASB goes in the remote chassis? Note: The existing DH+ port on the SLC is being used for programming & comms with a PLC5 and HMI.

3 - Just thought of something after reading another SLC expansion thread. Change out 16 pt modules for 32. For example the four IB16 modules could be condensed to two IB32. Right? The IA16 doesn't seem to have a 32 point counterpart. Nor does the OW16. That would free up 2 slots. Might be enough is we fill them with 32 point modules.

I may have just answered my own question.

Regardless, any advice you can provide would be very much appreciated. Thanks in advance.

 

[JesperMP]

Option 1. I would never expand between cabinets with the expansion cable. I have seen it done by others, and it is messy. And you need more than 4 feet anyway.

Option 2. This is the neatest solution. I think it will not be more expensive than the other two options, as it will be smooth sailing. You wont have to modify the existing cabinet - EXCEPT you have to find 1 more slot for the ASB module. Maybe exchange the 10-slot rack for a 13-slot rack if possible.

added: Option 2a. I am being brilliant here. Build an expansion cabinet, with an SLC500 rack, and move the SLC5/04 CPU to this rack. Then connect to the old cabinet and the old SLC500 rack with an 1747-ASB in the new rack, and a 1747-SN in the old rack in stead of the CPU. Then no other modification in the old cabinet is necessary.

Option 3. The 32-channel digital i/o modules use a ribbon cable to expand to separate terminal blocks. Some love these. Personally I hate them. Is a cludge. Besides you will have to cram in the extra terminal blocks, and if there is no space for an additional rack you wont find space for the terminal blocks either.

 

[TConnolly]

If you had the enclosure space then adding a second rack would be by far the easiest way to go. The interconnect does not take up a slot, you can start adding IO modules in the left most slot.

I seed Jesper thought the same thing I first thought: if you can shoehorn a 13 slot rack in then do that.

There is an option 4: Put in a device net scanner and add AB or Beckhoff Devicenet IO modules on the d-net.

 

[JesperMP]

Just a comment:

Who builds a control panel without there being space reserved for expanding the PLC ? Booooo !

 

[wildswing]

Just a comment: Who builds a control panel without there being space reserved for expanding the PLC ? Booooo !

LOL, that would be us. Long story, but this machine has been updated once before. It's an OEM setup from long ago, but we've been adding stuff. We started out with 4 spare slots in that chassis, but over the years, we've either bought or invented peripheral equipment that has used up those slots. Now we're doing it again. It's already a fairly large cabinet and real estate is scarce.

We might have room for a 13 slot.

Am I reading you guys right? To make a remote IO rack for a SLC, an ASB is added to the existing chassis as well as the remote chassis? The DH/RIO port on the SLC does not become the scanner?

Thanks. I didn't know that about the ribbon cable on the 32 point cards. Just curious. How long is (or can be) the ribbon cable?

 

[OkiePC]

You need a 1747-SN (RIO Scanner) in the same chassis with the CPU (any slot), and a 1747-ASB in the remote chassis CPU slot. Putting the CPU and SN module in the new chassis and making the old one the remote chassis means you don't have to shuffle things around to come up with a spare slot, since it would replace the CPU.

 

[JesperMP]

Am I reading you guys right? To make a remote IO rack for a SLC, an ASB is added to the existing chassis as well as the remote chassis? The DH/RIO port on the SLC does not become the scanner?

On an SLC5/04, the DH+ port cannot be reconfigured to work as a RIO port like you can on a PLC5 CPU.
You need a 1747-ASB module in the local rack (with the CPU), and a 1747-SN module in the remote rack (sits in the same place as the CPU would be).
edit: Oups, I got it wrong. OkiePC is right, the SN module is in the CPU rack, the ASB module is in the remote rack.

Thanks. I didn't know that about the ribbon cable on the 32 point cards. Just curious. How long is (or can be) the ribbon cable?

Look in page 12:
http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1746-in028_-en-p.pdf

 

[Mickey]

remote chassis means you don't have to shuffle things around to come up with a spare slot

Except addressing.

 

[LadderLogic]

My first hunch would be to install a DeviceNet or an Ethernet/IP module in the rack and then slave Beckhoff 'slice' I/O to it to you heart's content... This, of course, is assuming none of the additional I/O points need to be awfully (less than 5-10 ms latency) fast.

 

[wildswing]

OkiePC, about moving the processor to the new chassis. Would that not require re-addressing everything, as Mikey noted? I would think moving the wiring from one existing module to the new chassis would be easier. We'd only have to re-address 16 points at most to make room for the SN module. Am I missing something?

Thanks for the link Jesper.

LadderLogic, adding modern IO like DNet or Ethernet would be more than we need. The general area, currently run by a PLC5, is slated for a CLX upgrade next year. We're just trying to squeeze a little more IO into this SLC as easily as possible right now to accommodate some machine improvements & additions. The SLC will remain even after the CLX installation.

 

[OkiePC]

Yes, Mickey has a good point. You can move the references to the I/O data using search and replace and move the descriptions pretty easily though.

If it were mine, I would do what makes for the cleanest and most sensible end result, not which one takes an hour versus one minute to reconfigure in software.

Also, be aware that remote inputs and outputs may not be updated as quickly as local I/O. This can make a big difference for timing critical devices.

 

[wildswing]

Gotcha. Thanks.

 

[wildswing]

Hi fellas, Blowing the dust off an old thread for a little follow up.

Looks like we can make some room, so we've decided to go with the 32 bit modules.

First kick at the cat will be to swap out the 4 input modules.; I:2/0-15 through I:5/0-15. How will the SLC address the new 32 bit modules? Will I have I:2/0-31 through I:3/0-31 or something else?

 

[wildswing]

Never mind. Creating the new IO config, I just answered my own question.

 

[Helliana]

Will I have I:2/0-31 through I:3/0-31 or something else?

Correct. I:2.0 and I:2.1 will be your words, I:2/0-31 will be your individual bits.