
Chapter 2 Specification of Communication port for CPU module
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2.3.6 Connection method for RS-422 / 485 communication
Serial communication port of EHV-CPU can communicate with an interface of RS-422 / 485. Communication of
1:N stations can be performed using H-series dedicated control procedure (high-protocol) or a general-purpose
procedure with a general-purpose port command (TRNS 0, RECV 0). Figure 2.30 and 2.31 show examples when a
connection is made for 1:N stations.
And the connection for the communication in 1:1 made is the connection of only the first EHV-CPU.
(1) In case of RS-422
EHV-CPU
(32nd CPU)
EHV-CPU
(2nd CPU)
EHV-CPU
(1st CPU)
Host
SD (-)
SD (+)
RD (+)
RD (-)
Relay terminal
block
Relay terminal
block
Relay terminal
block
[7] RX
[6] RXN
[5] TXN
[4] TX
[7] RX
[6] RXN
[5] TXN
[4] TX
[7] RX
[6] RXN
[5] TXN
[4] TX
Figure 2.39 Connection for 1:N station communication by RS-422
(2) In case of RS-485
EHV-CPU
(32nd CPU)
EHV-CPU
(2nd CPU)
EHV-CPU
(1st CPU)
Host
SD (-)
[7] RX
[6] RXN
[5] TXN
[4] TX
SD (+)
RD (+)
RD (-)
Relay terminal
block
Relay terminal
block
Relay terminal
block
Twist pair cable
[7] RX
[6] RXN
[5] TXN
[4] TX
[7] RX
[6] RXN
[5] TXN
[4] TX
Figure 2.40 Connection for 1:N station communication by RS-485
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