Frame Format - Hitachi EH-150 Applications Manual

6.1.2

Frame format

The task code format of EH-ETH2 is shown in Figure 6.2. If you make an application program for host
computer, you should follow this format, which is different from the standard RS-232C protocol. The data
must be binary.
Cautions
EH-ETH2 can accept only binary data. ASCII data is not available.
Item
(a)
(b)
(c)
(d)
(a) (b)
(a) Termination command
H00: Normal operation. CPU will reply according to the requested task code.
HFF: If CPU receives the task code with HFF, the CPU will stop processing the last task code sent from a host
computer. If there is no processing to be stopped, this command is ignored.
H01 to HFE: EH-ETH2 discards the task code with command H01 to HFE.
(b) Through no.
Any number available. CPU will reply with adding same through number as in the command from host
computer. You can use it for debugging or your own purpose so that host computer can handle several
messages easily at the same time.
(c) LUMP address
See Section 6.1.3 for detailed information.
(d) Request/Response task code
See "Appendix B Task Code Specifications".
Caution
- If EH-ETH2 receives the 2nd task code (2) before the 1st task code has not executed, EH-ETH2 will reply "busy
response" against the 2nd task code (2)'.
Computer
Name
Termination command
Through no.
LUMP address
Request/Response task code
(c)
Figure 6.2 Frame format
To use control CPU module.
Through number to add request task code
H/EH series network address
H/EH series communication command code
Host
EH-ETH2
(1)
(2)
(2)'
(1)'
6-2
Chapter 6 Task code communication
Size(byte)
1
1
4
Max. 244
(d)
CPU module
(1)
(1)
(1)'