416F maximum number on IMs

Hllo guys;

The technical data and installation manuals of the S7-400 may be a bit confusing on this issue of expansion rack IMs, specially for inexperienced users.

Yes, you cannot use more than 6 IM460-0/1 for example with a S7-400 central rack. However, the total number of IMs shown in the ocumentation in a system is 21. The attached screenshot from the S7-400 module data will explain why:

The IM 460-1 (SEND IM) in the central rack can attach to up to 6 IM 460-0; one IM 460-3 in the central rack can connect to up to 6 IM 461-3 in their expansion racks.

So the total combination of Expansion racks available is 21 in a S7-400,; the maximum nuer of the different IMs to connect to these expansion racks is more limited. Look at the Technical Data for the CPU 461F-2 as an example, go down to the Hardware Configuration /Interface modules section.

https://support.industry.siemens.com/cs/pd/693839?pdti=td&lc=en-FR

These expansion racks and interface modules allow you to use S7-400 I/O modules and CPs in deported racks outside the CPU central rack. If you do nor mind using S7-300 modules for example you could also use Profibus remote racks, as ET 200M systems with IM 153-2, or Et 200S/ET 200MP deported I/O systems. There you could have as many as 124 seperate I/O racks, using Profibus-DP standards.

Hope this helps,

Daniel Chartier