User`s manual

Overview Base units
MELSEC System Q, Hardware 8 – 1
8 Base units
8.1 Overview
The MELSEC System Q offers a wide variety of main and extension base units. Up to four CPU
modules, one power supply, input/output modules and intelligent function modules can be
mounted on the main base units Q33B-E, Q35B-E, Q38B-E and Q312B-E. Two redundant
power supplies Q63RP or Q64RP can be mounted on the main base unit Q38RB-E, so that sys-
tem performance is increased. This main base unit has additionally 8 slots for up to four CPU
moduls and I/O or intelligent function modules.
The compact dimensions of the main base units Q32SB, Q33SB and Q35SB allow to build
space saving PLC systems.*
The extension base units Q52B and Q55B have no power supply slot and are supplied by the
power supply of the main base unit over the extension cable.
Input, output and intelligent function modules can be mounted on the extension base units
Q63B, Q65B, Q68B and Q612B. It has its own power supply for the modules. Use the extension
base unit Q68RB for two redundant power supplies Q63RP or Q64RP, to continue operation
while one power supply fails.
The base units are connected by extension cable.
* The main base units Q32SB, Q33SB and Q35SB have no connector for an extension base unit. Therefore the
connection of extension base units or GOTs is not possible via the extension bus.
8.1.1 Extension base units that can be combined with the main base unit
The following table shows the possible combinations of main and extension base units of
MELSEC System Q.
: Combination not available
: Combination available

Combination of base unit, power supply module and CPU

Applicable only in a redundant system.
Main base unit
Extension base unit
Q52B
Q55B
Q63B
Q65B
Q68B
Q612B
Q68RB Q65WRB

Q00JCPU

Q00UJCPU


Q33B
Q35B
Q38B
Q312B

Q32SB
Q33SB
Q35SB

Q38RB 
Q38DB
Q312DB

Tab. 8-1: Combination of base units