Voltage Drop When An Extension Base Unit Is Used - Mitsubishi Electric MELCEC Q Series User Manual

6. BASE UNIT AND EXTENSION CABLE
6.4

Voltage drop when an extension base unit is used

Since the extension base unit (QA1S5 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 QA1S5 B.
When using the QA1S5 B, make sure that the "IN" connector of the QA1S5 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)
Main base unit
Power
supply
module
Extension base unit (QA1S5
V R
I
When only the QA1S5 B is connected to the extension base unit
(a) Selection condition
4.75VDC or higher should be supplied to the "IN" connector of the QA1S5 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 QA1S5 B can be used if the voltage drop is 0.15VDC or lower
(4.9VDC - 4.75VDC = 0.15VDC).
B)
Extension
stage 1
Voltage drop to "IN" connector of the QA1S5 B is calculated as shown below.
Voltage drop (V) = Extension cable resistance (R)
at the QA1S5 B (I)
The condition where 4.75VDC or higher is supplied to the "IN" connector of the
QA1S5 B is satisfied when the voltage drop to "IN" connector of the QA1S5 B
(V) is 0.15V or lower.
*1: The sum (I) of the current consumption of the QA1S5
the QA1S5 B (I/O modules or special function modules) varies depending on which module
is to be mounted on the QA1S5
the module to be used.
Extension cable type
QC05B
QC06B
QC12B
QC30B
QC50B
QC100B
*1
B. Therefore, check it by referring to the user's manual for
6 - 7
Extension cable conductor
resistance
0.044
0.051
0.082
0.172
0.273
0.530
5VDC current consumption
B and the module to be mounted on