I am working on a project where we need to replace a PLC-5/25 SeriesA system with CLX.
The earlier system configuration is as follows
1.PLC-5/25
2.Rack1: 16-point DI modules - 13 nos. (I011 TO I025 - OCTAL)
3.Rack2: 16-point DI modules - 10 nos. + 16-point DO modules - 4 nos.(I030 TO I040 + O042 TO O043 - OCTAL)
4.Rack3: 16 point DO modules - 13 nos. (O050 TO O064 - OCTAL)
While mapping addresses of PLC-5/25 to CLX with 1-slot addressing can we add these modules to the CLX I/O configuration tree? Since when I add an 1771-ASB adapter, I get only 8 16-bit input words and 8 16-bit output words per rack; whereas the actual number is greater than 8 and it is also unclear whether it is being used in complementary mode.
Any help will be greatly appreciated.
Thanks

RCS

The old A-B addressing formats can be a little complicated, even for veterans. An important thing to understand is the difference between a "logical rack" and a physical chassis.

PLC-2, 3, and 5 I/O memory is logically organized the same, where 8 "slots" of I/O data makes up a "logical rack". Because you can have different addressing densities (1/2 slot, 1 slot, and 2 slot), different chassis sizes (4, 8, 12, and 16 physical slots) and possibly complementary addressing, you can have a lot of different addressing variations !

Consider your system's first chassis with the twelve 16-point Digital Input modules.

I:011
I:012
I:013
I:014
I:015
I:016
I:017
--------
I:020
I:021
I:022
I:023
I:024
I:025

Is there something else taking up the first slot ? Ordinarily this would begin addressing with I:010.

This is a single physical chassis, but it takes up 1 3/4 "logical racks" of I/O memory. You'd define this in RSLogix 5000 as two separate logical chassis. Rack 01 is a "Full Rack" and Rack 02 is a "3/4 Rack".

The second physical chassis spans begins addressing with Rack 03 for the first eight DI modules. The ninth DI module is the beginning of logical Rack 04. The five DO modules will then be addressed in the Output memory of Rack 04 as O:041, 042, 043, 044, 045.

This chassis would be defined in RSLogix 5000 as Rack 03, size "full rack" and Rack 04, size "3/4 rack".

The third physical chassis begins addressing at Rack 05, and would be defined in RSLogix 5000 as two logical racks, with Rack 05, size "full rack" and Rack 06, size "1/2 rack".

If you posted the precise settings of the DIP switches on the back of the PLC-5/25 and each 1771-ASB, that would determine the addressing mode for certain. This does sound to me like an ordinary "1-slot addressing" system.

Some of your addressing notes do not sound standard. The I/O in the chassis with the PLC-5/25 is usually Rack 0, and you've described some of the addressing as going beyond the normal I/O size (the last one should stop at 063, for example). If you want a definitive answer, post a more specific description of the system and I'll take another look at it.

Ken mentions that addressing is tricky and he is right.

The PLC5 scheme for addressing bits was as follows:
/00 ; /01 ; /02 ; /03 ; /04 ; /05 ; /06 ; /07 ; /10 ; /11 ; /12 ; /13 ; /14 ; /15 ; /16 ; /17

But with ControlLogix it will be
/00 ; /01 ; /02 ; /03 ; /04 ; /05 ; /06 ; /07 ; /08 ; /09 ; /10 ; /11 ; /12 ; /13 ; /14 ; /15

This means that old wire label I:010/14 really comes in as bit 12 in CLGX. Beware.

[attachmentid=5304]Thanks Ken!
Unfortunately I still can't get thru the addressing and Logix I/O configuration issue.
I am attaching the PLC-5/25 program along. Can u give me the Logix I/o Config as well as addressing to be done in the converted Logix program. I have done similar conversions for PLC-5/60 with 1794-ASb adapters, but this case seems to be confusing. Also how can we detect the complementary addressing system.
Thanks a lot again.

Your description of a chassis with 13 Input modules as well as a chassis with 13 Output modules does sound like the kind of system where Complementary I/O addressing has been used. Only a direct examination of the DIP switches on the back of the 1771-ASB adapter modules will tell you for absolutely certain.

But the rest of the addressing points to Single-Slot non-complementary addressing being used.

Only one point in Rack 00 (the processor-resident chassis) is used, making me think it is empty except for one module.

The first chassis comprises Logical Rack 01 and Logical Rack 02
The second chassis comprises Logical Rack 03 and Logical Rack 04
The third chassis comprises Logical Rack 05 and Logical Rack 06

The usage of the I/O data in each chassis points to that chassis being addressed in the Logical Rack memory I noted above, which matches your descriptions. I assume you got those from labels on the modules and chassis or from wiring labels.

Again, the only way to be absolutely sure of the Logical Rack number and the Addressing Mode is to examine the DIP switches on the 1771-ASB. Until then, everything else is reasonable conjecture.




Think of the three physical 1771-A4B sixteen-sot chassis as two logical racks of I/O memory each:

[Rack 01, Rack 02]
[Rack 03, Rack 04]
[Rack 05, Rack 06]

Attached is an RSLogix 5000 (v15) example of how to configure these chassis with a 1756-DHRIO.

and while you're nailing down those DIP switch settings on the ASB modules, it might also be a good idea to find out exactly how the DIP switches are set on each of the chassis backplanes ... there are eight of these and they will be available while you have the ASB removed from the chassis - so write these down while you're at it ...

PS edit ... I realize that this is probably exactly what Ken has already been asking for ... I just wanted to specify exactly WHERE to look for these particular DIPs ... they are part of the CHASSIS - not on the processor - and not on the ASB - and you can't see them until the processor or ASB has been removed from the chassis ...

Which proves how long it's been since I pulled a 1771-ASB out of a chassis.

Ron is, as usual, absolutely correct. The DIP switches that set the chassis addressing modes are on the backplane of the chassis, not the 1771-ASB adapter.

Thanks, Ron !

Set the mode to 1/2 slot addressing if you are using 32 bit modules. Switches 4 and 5 on back plane chassis of ASB adapter are used for this purpose. Set them to
Switch 4=ON switch 6=OFF for 1/2 slot addressing
for only 16 bit modules it is recommended to use 1 slot addressing
Switch 4=ON switch 5=OFF

Select the starting rack number from ASB adapter and start addressing from that number