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AC800 Series Intelligent Machine Controller Hardware User Guide 5 Wiring
Wiring of P_OK power failure detection signal: See the above gure. When a power failure occurs, the
signal turns from ON to OFF, and the PLC saves data and shuts down.
Wiring of power-on signal: If a power failure occurs, take measures according to the following situations:
■ If the power is recovered before the UPS runs out of power, press the power button on the PLC to turn
it on. If the PLC is in a cabinet and it is dicult to reach the button, it is recommended to connect the
24V power supply to the signal through a non-self-lock switch which can be used to start the PLC.
■ If the power is recovered after the UPSｒｕｎｓ out of power, a UPS charging signal is sent to the PLC
and the PLC starts.
Normally, only the two signals associated with P_OK must be connected. The other status
signals can be connected as needed.
5.3.3 RS485 Bus Wiring Instructions
The RS485 bus topology is shown below. Using shielded twisted cables to connect 485 bus is
recommended. The 485+ and 485- terminals are connected with a twisted pair cable. A 120 Ω termination
resistor is attached to both ends of the bus to prevent signal reection. All RS485 reference grounds are
connected with each other. Up to 32 nodes can be connected and the distance between each node and
the bus must be less than 3 m.
SFTJTUPS
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Ē Ē
$(/%
$(/%
.BTUFS
4MBWF
4MBWF/
%*1TXJUDI %*1TXJUDI
6TFUIFTXJUDIUP
TFUUIFUFSNJOBUJPO
SFTJUPS
Figure 5-8 RS485 communication connection
Multi-node connection
When there are a large number of nodes, the daisy chain topology must be used. If a branch line
connection is required, the distance from the bus to the node should be less than 3 m and as short as
possible. Star connection is strictly prohibited. The following diagram shows the common bus topologies:
.BTUFS
4MBWF
4MBWF
4MBWF
4MBWF
/
34CVT
3FDPNNFOEFE
Figure 5-9 Daisy chain
.BTUFS
4MBWF
4MBWF
4MBWF
4MBWF
/
34CVT
N
N
N
3FDPNNFOEFE
Figure 5-10 Branch line
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