Omron SYSMAC C Series Operation Manual page 29

Specifications and General Information
Precautions
1, 2, 3...
Voltage Input and
Differential Output Signals
1, 2, 3...
12
Abide by the following precautions when using separate power supplies for the
input points.
1. Use shielded twisted-pair cable for external connections.
2. Connect the positive and negative terminals of any unused input points to
the shield terminal.
3. Use separate power supplies for input points 1 and 2 whenever possible. In
this case, the shield terminal must be shorted to the negative terminal, as
shown in the diagrams above. Failure to do so may cause errors of several
percent in the output data.
4. If the same power supply must be used for input points 1 and 2, connect the
wiring as shown in the diagram below.
The connections shown in the previous diagrams should not be used for a
single power supply, because the internal connections of the shield termi-
nals for input points 1 and 2 inside the Unit cause interference between the
input points and inaccurate data will result.
Connect as shown in previous diagram (1) for voltage input signals in com-
mon mode.
Connect according to one of the following methods when the same power supply
is used for input points 1 and 2.
1. Connect shield terminal to signal supply common terminal.
Input device
+
+V
–
0 V
+
+V
–
0 V
Shielded
twisted-pair
cable
2. Connect resistors from the shield to the positive and negative terminals.
Input device
R: 15 kΩ
+
+V
–
0 V
+
+V
–
0 V
Shielded
twisted-pair
cable
0
+Voltage input
1
2
– Input
3
Shield
4
5
+Voltage input
6
7 – Input
8
Shield
9
0
+Voltage input
1
2
– Input
3
Shield
R
4
5
+Voltage input
6
7 – Input
8
Shield
R
9
Section 2-1
Input point 1
Input point 2
Input point 1
Input point 2