Hitachi EH-150 Series - Connection of Communication Port; Connection of RS-232 C Interface

Chapter 4 Installation
4 - 4
4.3 Connection of communication port
4.3.1 Connection of RS-232C interface
The communication interface is selectable for both port 1 and port 2. Select RS-232C with the communication
setting switch. (In case of port 1, the hardware before Rev. 10 supports RS-232C only.)
Table 4.4 RS-232C interface
Terminal layout
No.
Symbol
Signal name
Diagram of Internal circuit
8
1
.
.
.
.
8
1
.
.
.
.
1
SG
Ground for signal
Micro processor
1) SG
2) CD
3) CS
4) ER
5) SD
6) RD
7) DR
8) RS
2
CD
Carrier detect
3
CS
Clear to Send
4
ER
Communication enabled signal
5
SD
Data sent from EH-SIO
6
RD
Data received by EH-SIO
7
DR
Peripheral units connected
signal
8
RS
Transmission request signal
 Signal name and Connector pin arrangement
Table 4.5 Signal name (EH-SIO side) and connector pin arrangement (RS-232C Port)
Pin
No.
Signal Name
Symbol
Signal Direction
Specifications
EH-SIO
External
device
1
Signal for Ground
SG
--
--
Ground for communication
2
Carrier Detect*
2
CD


A career is detected while it is connectable with the
external device.
EH-SIO does not receive data when it is Low.
3
Clear to Send*
2
CS


It means that external device can be received.
EH-SIO does not transmit data when it is Low.
4
Data Terminal Ready*
2
ER*
1


It means that data (or command) is receivable.
Control by the user program is possible.
5
Send Data
SD


Data from EH-SIO.
6
Received Data
RD


Data from external device.
7
Data set Ready*
2
DR


It means that external device can operate.
It becomes “port connection error” at the time of Low.
8
Request to Send*
2
RS*
1


This signal is turned on to transmit data.
Control by the user program is possible.
*1 When EH-SIO operates in free protocol mode, RS and ER can be controlled by the control register. (A setup always turned
on is also possible.) Please refer to "5.2.3 Detail of output register".
*2 When EH-SIO operates in Modbus mode, control signals are not used. (It communicates without watching these signals.)
In addition, in the case of Hi-Protocol mode, control signals CS, CD are not used too.
When using in Hi-Protocol mode
There is a signal line by which the input / output directions differ in the communication port of CPU module and
EH-SIO. (Pin No.3)
Even if you are a cable with the actual result which communicated with CPU module, please be sure to check
the signal line of a cable.
(In Hi-Protocol mode, since “CS” signal is not used, the connection with external device is unnecessary.)