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6 Examination of System Configuration
6.5 Expansion of Main Unit
77
FX3G Series Programmable Controllers
User's Manual - Hardware Edition
1
Introduction
2
Features and
Part Names
3
Product
Introduction
4
Specifications
5
Version and
Peripheral
Devices
6
System
Configuration
7
Input/Output
Nos., Unit Nos.
8
Installation
9
Preparation and
Power Supply
Wiring
10
Input Wiring
In the case of DC power type main unit
The allowable extension to the DC power supply type main unit varies depending on used extension blocks
as described below.
1. When connecting only the input/output extension block
Input/output extension blocks of up to 32 points can be connected.
2. When connecting the input/output extension block and special function block
Input/output extension blocks of up to 16 points can be connected.
Only 1 special function block can be connected.
3. When connecting only the special function block
Up to 2 special function blocks can be connected.
When extension of the above points 1 to 3 is carried out and further extension is required, determine whether
extension is possible using one of the following methods:
For details, refer to the following.
→ Refer to 6.6 Expansion of FX2N Series I/O Powered Extension Unit.
6.5.1 When adding input/output extension blocks using the 24V DC service power supply
of the main unit
When extension is prohibited in the AC power supply type main unit due to restrictions in connection
described above, it is possible to add extension blocks using the 24V DC service power supply of the main
unit.
For adding extension blocks using the 24V DC service power supply, it is necessary to examine again
whether extension is possible for all of extension blocks selected in the preceding subsection and extension
blocks to be selected in this subsection.
Note that only up to two network-related special function blocks can be connected including extension to the
main unit.
1 Confirm the priority of all extension blocks to be connected to the main unit.
The priority is set to each extension block to be connected, and required to judge the possibility of
extension to the main unit. The priority is determined by the extension block type without regard to
the connection position.
When the extension power supply unit (FX
3U
-1PSU-5V) is used and the nearest upstream unit to
the extension power supply unit is the main unit, the priority should be considered also for input
extension blocks (including the FX
2N
-8ER-ES/UL and FX
2N
-8ER) extended to the extension power
supply unit.
2 Judge whether extension to the main unit is possible.
Judge the possibility of extension to the main unit for all extension blocks in turn, starting from the
extension block having the highest priority confirmed in step 1. Consider that 16 input/output points
are provided in each of the FX
2N
-8ER-ES/UL and FX
2N
-8ER. Eight output points have higher prior-
ity over 8 input points. For judgment about the possibility of extension to the main unit, refer to the
Section 6.5.
Input extension
block
FX2N-8ER-ES/UL
FX
2N-8ER
Priority 2 Priority 3Priority 1 Priority 4
<Priority>
>>>
Special function
block
Output extension
block
Priority LowPriority High