Hitachi Hidic EH-150 Applications Manual page 41

Preliminary Rev.03
Chapter 6 Task code communication
There is, the communication agreement called a task cord that prescribed an original command to the H
series. It is possible to communicate between a host computer and EH-ETH by using this task cord.
Features of task code communication
- No need ladder program for task code communication.
- It is possible to write/read out a ladder program from a/the host computer to CPU module. Also, it is
possible to set and also, monitor data to the inside output of a CPU module.
- EH-ETH transmit the request task code to EH-CPU448 to omit the header information of TCP(or UDP)
packet issued by a host computer. This to, EH-ETH transmit response task code to a host computer to add
TCP(or UDP) packet header information.
6.1 H series communication specification
The detailed function of each task code(command) is described in this chapter.
6.1.1 Outline
The following shows the outline of H series communication specification.
Logical layer
Data link layer
Physical layer
Module name
EH-ETH use the uni-directional procedure at data link layer. At this uni-directional procedure, only a host
computer can start the communication to H series module. The task code communication which EH-ETH
supports functions as passive protocol to response to a host computer.
As explained above, for H-series, the protocol is defied so that the host computer can access all CPU in the
network of H-series.
The following five functions of H-series are available to users.
(1) CPU control
(2) I/O control
(3) Read memory
(4) Wrtie memory
(5) Response
To utilize these functions, various task codes are to be assembled in the host computer program.
See the EH-150 application manual (NJI-280B(X)) Appendix 3 Task Code Specifications for detailed
task code (command code). And see next chapter for data format.
The contents of this manual might be changed without notice.
Functions viewed from user7s eyes
I/Control CPU control memory read/write response
Combination of task codes
Protocol for each task code
TCP/IP, UDP/IP
IEEE 802.3
EH-ETH
Figure 6.1.1 Out line of the communication protocols for H series
: RUN/STOP control of CPU, set/reset of occupancy, Read CPU status etc.
: Various monitors
: Read programs etc.
: Clear all, transfer all etc,
: Various response from CPU
Chapter 6 Task code communication
Communication procedure 1,2
RS-232C, RS-422, RS-485
EH-CPU448
6-1