Serial Port Specifications; Physical Layer Interface; Rs-232C Communication Specifications - Hitachi MICRO-EHV+ Applications Manual

Chapter 2 Specifications
2.9

Serial port specifications

2.9.1

Physical layer interface

5 VDC
Pin
Signal name
No.
[1] SG
[2] VCC
[3] DTR1(ER)
[4] N.C
[5] SD1(TxD)
[6] RD1(RxD)
[7] N.C
[8] RS1(RTS)
2.9.2

RS-232C communication specifications

Specifications of RS-232C communication are shown in Table 2.8.
Item
Transmission speed
Interface
Maximum cable length
Connection mode
Synchronization method
Supported function
Transmission method
Transmission code outgoing sequence
Error control
Transmission unit
Maximum message length
*: Communication in 115.2kbps could be unstable depending on PC. If so, change the baud rate to 57.6kbps or slower.
[1] SG
[2] VCC
[3] DTR1(ER)
[4] N.C
[5] SD1(TxD)
[6] RD1(RxD)
[7] N.C
[8] RS1(RTS)
Figure 2.1 Circuit diagram and Pin No. of RS-232C
Table 2.7 List of signal of RS-232C
Direction
PLC Host
Signal ground
5 V DC is supplied. (Protective fuse is connected.)
When PLC is ready to communicate, this signal is high.
Don't connect.
Sending data from PLC
Receiving data to PLC
Don't connect.
When PLC is ready to receive data, this signal is high.
Table 2.8 RS-232C communication specifications
4,800 bps / 9,600 bps / 19,200 bps / 38,400bps / 57,600bps / 115,200bps *
Modbus-RTU master/slave, General purpose communication
Vertical parity check, sum check, overrun check, framing check
Meaning
Specifications
RS-232C
15 m
1 : 1
Start-stop synchronization
Serial transmission (bit serial transmission)
Send out from the lowest bit in character
Message unit (variable length)
1,024 bytes (including control characters)
2 – 12
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]