Configuring 1771 RIO Chassis

Hello all.
I need a little help setting up some 1771 ASB adaptors and chassis. I have a PLC 5 system with 4 RIO chassis which was never finished when installed. One of the RIO chassis is set up and working correctly (Racks 1,2,3). The other 3 RIO chassis (in substations) haven't been setup, but code was written in the ladder logic, so I know which logical racks need to be set up in each substation.

How do I set up the switches for the ASB's for the rack numbers.
I have:
ASB Sub 2 - Racks 6 & 7
ASB Sub 3 - Racks 4 & 5
ASB Sub 4 - Racks 10 & 11.

I under stand SW1 1-6 is the IO Rack number, but is this set to the first logical rack in that chassis? I.e. ASB Sub 2, I would set to 111001, then the PLC will know that this chassis starts at logical rack 6 so the next logical rack will be 7?

Sorry for the long winded post, im a bit confused here.

Hi Oceansoul,

it always was a bit confusing when you start looking at switch configurations for RIO racks, but it does get clearer....

Can you access the working racks to check the switch settings, as then they should be the same, except for the starting rack number.

Yes, your switch S1 on the 1771-ASB have to be set for the first logical rack that is connected - ASB Sub 2 - Rack 6 group 0
Switch S2 is for the comms speed - usually the fastest you can do.

You will also need to remember to set the switches on the I/O chassis for last state/restart/type of addressing(1/2 slot, 1 slot, 2 slot).

What size are your racks?

Hopefully that helps for starters....

I don't think I will be able to pull the existing ASB that is in and working unfortunately. Maybe, but unlikely.

I've checked the addressing mode in the PLC code, and its 1/2 slot. I guess this has to be the same for all IO chassis? Also the RIO baud is 57.6k. I copy this into DIP switch on the ASB's. After setting what to do with the outputs (all off), restarting etc its just a matter of setting the Rack starting address? Do I then just add my extra racks (logical racks) into the IO listing as full racks?

I forgot to make a note of the chassis size, think its 7 slot. There are 4 16bit input cards then a relay output card. Makes sense with the half slot addressing.

Photo of current setup.

woah there, Oceansoul.....look at the pic you posted...

1771-A1B Rack addressing : 1-slot...not 1/2 slot, so you have maximum 16 channels per slot.
1/2 slot is 32 channels per slot, and 2 slot is maximum 8 channels per slot.

All racks do not have to have the same channel density, as long as they are numbered and addressed correctly. They do have to have the same baud rate if they are all off the same channel, which you have there as 57.6k.
Looks like you are only using Ch 1B for RIO, so you will be daisychaining the comms cable to each one, I assume? If so, watch for the positioning of the end of line resistor on DH+.

Rack sizes are 4,8,12 or 16 slots.

I am surprised that you are resurrecting this as RIO are classed as obsolete - I tried to buy 1794-ASB (flex I/O) and they are not available, but much newer than 1771 cards etc. The 1771-ASB modules had issues some years back, so not sure which revision you have, but check the manual carefully as the latter versions may have had a dip-switch change.