RIO addressing in PLC5.

Hey guys

How to address plc5 rio. I completely understand how addressing is made to local input and output but we how do we address over dh+ RIO. Please let me know.,

PS: we have got 7 racks with two slot adressing

It's actually a fairly complex addressing system, but at least you've narrowed it down to "two-slot addressing".

First: DH+ and RIO use the same physical wiring but are different protocols with different features.

To tell you how each remote chassis of yours is addressed, you would have to post all the details about the DIP switches on the adapters and what size the chassis are.

In A-B Universal Remote I/O syntax, an address "group" is one 16-bit Word of Input data and one 16-bit Word of Output data.

"Two-slot" addressing means that each I/O address "group" takes up two physical slots. Usually this means alternating Input and Output modules.

The best document to read to learn PLC-5 addressing is the PLC-5 Enhanced and Ethernet Controller User Manual, Publication 1785-UM012.

So you mean the Local rack can be addressed as two slot and Remote Chasis can be addressed as single slot.??

Yes. The local chassis and the remote chassis do not have to use the same density setting (1/2, 1, and 2-slot modes), nor do all remote chassis have to use the same addressing mode.

This is flexible, but can also be complicated.

When you need advice on RIO addressing, it is absolutely necessary to include all of the DIP switch settings and inventory of the modules in a chassis.

Correct me if am wrong .
Alternating Input and Output modules is always two slot addressing ??

Alternating 16-point Input and Output modules is *usually* two-slot addressing.

There's nothing to keep you from doing the same thing in a one-slot addressing chassis and wasting half of your I/O memory space.

An example: A remote chassis is an eight-slot 1771-A2B chassis with 1771-IA16 and 1771-OA16 input and output modules (120V AC) in it. The chassis has a 1771-ASB adapter configured for Rack 03, with 2-slot addressing.

This chassis will take up "1/2 Rack" of RIO address space.

The modules are addressed as follows:

Slot 0, 1771-IA16 I:030/00-15
Slot 1, 1771-OA16 O:030/00-15
Slot 2, 1771-IA16 I:031/00-15
Slot 3, 1771-OA16 O:031/00-15
Slot 4, 1771-IA16 I:032/00-15
Slot 5, 1771-OA16 O:032/00-15
Slot 6, 1771-IA16 I:033/00-15
Slot 7, 1771-OA16 O:033/00-15

Again, all of this is in the PLC-5 User Manual. If you are having difficulty understanding a particular system, post details about that system.

I've been corrected (by somebody more alert) about bit numbers in PLC-5 I/O addressing; the bits are numbered 00 through 17, not 0 through 15.

PLC-2, PLC-3, and PLC-5 systems use Base 8 "Octal" addressing for I/O addressing. Only the digits 0,1,2,3,4,5,6,7 are used.

This can cause confusion because the PLC-5 uses Decimal addressing for Integer and Bit registers, and the SLC-500, MicroLogix, and ControlLogix use decimal addressing exclusively.

So always be careful when using Octal addressing to be sure that you are really looking at the correct bit; bit "10" is really the ninth point on the module.

It trips up even veteran programmers !

A-B Addressing for PLC-5 I/O racks

This is how I keep it straight.

If you want your card arrangement totally unrestricted, it follows this pattern:
2-slot addressing = 8 point cards
1-slot addressing = 16 point cards
1/2-slot addressing = 32 point cards

I think of this as the "default" configuration.

If you can tolerate alternating input cards and output cards in pairs, it follows this pattern:

2-slot addressing = 16 point cards
1-slot addressing = 32 point cards
1/2-slot addressing = not useful

I think of this as the "upgrade" configuration. Many older PLC-2 and PLC-5 PLCs were originally installed with 8 point cards and 2-slot addressing. Over the years they were upgraded by replacing 8-point cards with 16-point cards. For example, if you had 2 8-point output cards in the same module group, you could replace them both with one 16-point output card and gain a spot for a new 16-point input card.

I don't think I would ever build a new system with alternating input and output cards. The ratio is usually more like 4 inputs for every output in my experience so I don't find that arrangement very useful. But when you need to squeeze a few more I/O into an existing system, definitely.

Please don't anybody raise the subject of complementary chassis !!

Ken Roach said:

So always be careful when using Octal addressing to be sure that you are really looking at the correct bit; bit "10" is really the ninth point on the module.

It trips up even veteran programmers !

Click to expand...

Lost count of the number of times I've seen that happen, and to add to Ken's excellent point, it is always best to say "1" "5", instead of 15, it hammers home the notion that we are not using a decimal (base 10) numbering system. Pretty much the same way we would say "3" "E" "5" "7" for hexadecimal numbers, largely because we can't speak a lot of hex numbers as decimal

daba said:

Please don't anybody raise the subject of complementary chassis !!

Click to expand...

Daba

I have heard of this but never seen it used. Is it a PITA to use / setup?

What is the advantage?

The Plc Kid said:

Daba

I have heard of this but never seen it used. Is it a PITA to use / setup?

What is the advantage?

Click to expand...

It is all about using the allowable I/O space for each processor, and is similar to using 2-slot addressing with 16-bit cards, populating each "group" of 2-slots with both an input and an output card.

Extend that idea to, for example, 2 physical 8-slot chassis, one full of Input cards, and the other full of output cards. Both chassis can have the same RIO address.

Extend the idea further, and a chassis that has..
I-O-O-I-I-O-I-O can have a complementary chassis that has..
O-I-I-O-O-I-O-I

It is not a PITA to setup and use, but a real PITA for the poor tech who doesn't understand it to deal with any i/o problems on the swing shift. He'll quickly discover the two RIO adapters set to the same address and will do a WTF?

I would avoid using it, unless you can 100% guarantee that anyone who may have to work on the system is au fait with the technique, something that is difficult to achieve in reality.