Mitsubishi Melsec-Q Series User Manual page 171

6.1.5 Guideline for extension base units
Since the extension base unit (Q5 B) is supplied with 5VDC from the power supply module on the main base unit, a
voltage drop occurs at extension cables.
Improper I/O may be provided if the specified voltage (4.75VDC or higher) is not supplied to the "IN" connector of the
Q5 B.
When using the Q5 B, make sure that the "IN" connector of the Q5 B is supplied with 4.75VDC or higher.
And it is recommend to connect it with the shortest possible extension cable right after connecting the main base unit,
so as to minimize the effects of voltage drop.
(1) When only the Q5 B is connected to the extension base unit
(a) Selection condition
4.75VDC or higher should be supplied to the "IN" connector of the Q5 B in the final extension base.
(b) How to calculate voltage to "IN" connector
The 5VDC output voltage of the power supply module on the main base unit is set to at least 4.90VDC.
Therefore, the Q5 B can be used if the voltage drop is 0.15VDC or lower (4.9VDC - 4.75VDC = 0.15VDC).
Main base unit
Power
supply
module
V1 Extension base unit (Q5
R1
I1
V2
Extension base unit (Q5
R2
I2
V7 Extension base unit (Q5
R7
I7
Figure 6.9 System configuration
Table6.18 Extension cable conductor resistance
Extension cable type
B)
Extension
stage 1
B)
Extension
stage 2
B)
Extension
stage 7
CHAPTER6 BASE UNIT AND EXTENSION CABLE
Extension cable conductor
QC05B
QC06B
QC12B
QC30B
QC50B
QC100B
1
2
3
4
5
6
7
resistance
8
0.044
0.051
0.082
0.172
0.273
0.530
6 - 16