H Series Protocol (Hi-Protocol; Outline - Hitachi EH-150 Series Applications Manual

A.3

H series protocol (Hi-Protocol)

A.3.1

Outline

Hi-Protocol is special protocol between communication module of H/EH series and a host computer (here after
host) or HMI. CPU module, COMM module, remote module, CPU link module, and Ethernet module, etc. of
Hitachi H/EH series are able to handle Hi-protocol.
Task code (command code) and transmission control procedures are concretely specified in Hi-protocol. The outline
of Hi-Protocol is shown in Figure. A.4.
I/O Control CPU Control Memory Read/Write Response
Transmission control procedure 1
Transmission control procedure 2
In case of serial communication, physical level is RS-232C, RS-422 or RS-485. The procedure called one-sided
startup is used on a data link level. This one-sided startup means that only a host can request to start
communication.
In addition, although Hi-Protocol covers to access all CPUs over network, Hi-protocol on EH-SIO is limited that
covers only CPU module mounted in the same base with the EH-SIO.
The functions seen from users
Task code combination
Task code protocol
RS-232C/ RS-422/ RS-485
CPU module, EH-SIO
Figure.A.4 Outline of H/EH series communication protocol
TCP/IP
UDP/IP
IEEE 802.3
EH-ETH
A - 7
Appendix
Logical level
Data link level
Physical level