1734 I/O with empty slots question

I am working on a project that the design engineer left empty slots on 1734 I/O modules with a 1734 ANCR, the PLC is a 1756-L61.

Example: the first 3 slots have 1734 analog inputs then leave 5 unpopulated I/O slots then has 1 1734 analog output module and 3 unpopulated slots and then 5 1734 digital output modules. I am running RSNetworx and it shows all the I/O modules sequentially with no empty slots. I have the RSLogix5000 configuration setup to match the engineering and I can't get the I/O to talk. Will this configuration work or do all the slots have to be populated to the last used I/O module on the rail.

Think of the POINTBus backplane like a tiny DeviceNet. The address of a POINT module is set in software and stored in onboard NVRAM on the module, not by its physical position on the network. Most often, modules are installed side-by-side and the Sequential Auto Address feature is used to assign them sequential addresses.

To make your adapter work the way it's laid out in RSLogix 5000, you will have to manually assign "slot number" addresses to the modules that correspond with their physical locations.

RA sells a module that's specifically built for this kind of situation where users will omit or include 1734 POINT modules based on system needs but they want the exact same wiring and addressing. The 1734-ARM Address Reserve Module just sits in a POINT terminal base and responds to the browse and the Sequential Auto Address feature.

Having 9 modules in an assembly of 17 terminal bases seems to be a lot of empty space, but I'm sure your designer had his or her reasons.

Thanks for the information. I will inform our engineer about the 1734 ARM modules as one other support person had recommended populating all empty terminals but was told by another empty terminals could be left.

The reason for the spaces is customer specification for the possibility of future expansion and retaining continuity of the I/O layout. I didn't have my drawing sets with me so I came up with an example of modules and terminals so the actual count may be off.

I'm coming from DDC (HVAC controls) programming so getting the terminology right with this product is an ongoing process.