Omron CJ2 CPU UNIT - A-4-3 Applicable Connectors and Recommended Cables; Connections for Echoback Test; Example for CJ2 H CPU Unit; Examples of Recommended RS-232 C Wiring

Appendices
A-132
CJ2 CPU Unit Hardware User’s Manual
z Connections for Echoback Test
We recommend the following wiring methods for RS-232C, especially in environment prone to noise.
• Use shielded twisted-pair cable for communications cables.
• Use a twisted-pair cable for each signal line and SG (signal ground) to connect the CPU Unit to a
communications partner. Also, bundle all the SG lines at the Unit and at the other device and connect
them together.
• Connect the shield line of the communications cable to the hood (FG) of the RS-232C connector at
the Unit. Also, ground the protective earth (GR) terminal of the Power Supply Units on the CPU Rack
and the CJ-series Expansion Racks to a resistance of 100 Ω or less. The following example shows
connecting SD-SG, RD-SG, RS-SG, and CS-SG for Serial Communications Mode using a twisted-
pair cable using the peripheral bus.
Note The hood (FG) is internally connected to the protective earth (GR) terminal on the Power Supply Unit
through the CPU Rack. FG can thus be connected by connecting the protective earth (GR) terminal on the
Power Supply Unit. The hood (FG) is also electrically connected to pin 1 (FG), but the connection resistance
between the shield and the FG is smaller for the hood. To reduce contact resistance between the hood (FG)
and the FG, connect the shield both to the hood (FG) and to pin 1 (FG).
Use the following connections.
A-4-3 Applicable Connectors and Recommended Cables
Examples of Recommended RS-232C Wiring
Example for CJ2H CPU Unit Example for CJ2M CPU Unit
RS-232C port
Signal name
SD
RD
RS
CS
FG
ER
DR
Pin No.
2
3
4
5
1
8
7
RS-422A/485 port
Signal name
SDA-
SDB+
RDA-
RDB+
FG
Pin No.
3
4
1
2
5
XM2S-0911-E
Hood
Shield
SG signal line
CPU Unit
External device
Signal
name
Pin
No.
Signal
name
SG signal lines
bundled together
Aluminum foil
2
3
4
5
9
1
SD
RD
RS
CS
SG
FG
FG
RD
SD
CS
RS
SG
FG
GR
CPU Unit
Power Supply Unit
Ground to 100 Ω
or less
Hood and GR connected
internally.
The hood will be grounded
if the GR terminal is grounded.
POWER
PA205R
DC24V
AC240V
OUTPUT
RUN
INPUT
AC100-240V
L2/N
L1
COMM
GR
Power Supply Unit
Ground to 100 Ω
or less
Pulse I/O Module