Configuring Hardware and Communication Connections STEP 7.pdf

2.1.3 Special Rules for M7-300
Configuring Central Racks
When you configure an M7-300 module group, each module in the group occupies
a slot.
If the first module of the module group is an M7-300 CPU, then the next slot after
the module group can be occupied only by either an interface module or it remains
empty.
Module Group (M7-300)
An M7-300 module group is formed when expansion modules (EXM) or a massstorage
module (MSM) are used to extend an M7 CPU or an M7 FM (function
module). All modules in the module group are connected with each other via their
AT-ISA bus and form, in effect, the automation computer.
First arrange the basic module (M7 CPU or M7 FM) and then the expansion
modules in the configuration table. Otherwise you will not be able to insert the
expansion modules.
Arranging Modules in a Module Group (M7-300)
A module group results in new slot rules:
• The M7 CPU or the expandable M7 FM is always the first module in the
module group.
• The mass-storage module (only one can be inserted) is always the last module
within the module group.
• The M7 CPU or M7 FM may not be expanded by more than three modules
(MSM or EXM). The permitted number of expansion modules is documented for
the appropriate M7 FMs.
Configuring Hardware and Communication Connections with STEP 7
A5E00706939-01 2-3