Omron CQM1H-CLK21 - Manual (Page 119)

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C200HX/HG/HE Controller Link Units Section 4-3
Note 1. Do not use the same operating level for more than one Unit mounted to the
same PLC. An error will occur is the same operating level is set twice.
2. Operating levels are used by the CPU Unit to distinguish different Commu-
nications Units. Each node can have a different operating level, i.e., it is
not necessary to use the same operating level for all nodes in the same
Network.
4-3-4 Terminating Resistance
Turn ON the terminating resistance using the switch on the bottom of the Unit
for the Units of both ends of the Network. The terminating resistance is
required at both ends of a Network to absorb unnecessary signals and reduce
noise.
The Controller Link Unit has built-in terminating resistance, which can be con-
nected simply by turning ON the slide switch.
Note 1. Always turn OFF the PLC’s power before setting the terminating resistance
switch.
2. Turn ON the switch to connect terminating resistance at the nodes at both
ends of the Network and turn OFF the switch at all other nodes. Normal
communication cannot be performed in the Network unless all the nodes
are set properly.
3. The TER LED indicator will light when the terminating resistance switch is
set to ON.
Pin 4 Operating level Node
OFF (factory default) Operating level 1 Set all the nodes on the
Network to either Operat-
ing level.
ON Operating level 0
Operating level 0
Operating level 1
Operating level 0
Operating level 1
Note It is not necessary to use the same operating
level for all nodes in the same Network.
Bottom switch Terminating resistance
OFF (factory default) Not connected.
ON Connected.
ON