Communication manual TOHO ELECTRONICS INC.
DWG.No. 4B-6829-A
- 4 -
Section
３
Communication Outline
３．１．
Communication Procedures
This product returns the “response message” as a reply to the “request message” that will be sent by the upper computer.
Therefore, the transmission will never be initiated by this product.
High-level computer
This product
Request message
Response message
Request message
Response message
Transmitted by a highlevel
computer
Transmitted by this
product
Transmitted by a highlevel
computer
Transmitted by this
product
0-250ms
2 ms or more
Response delay
３．２．
Kinds of Message
■
Kinds of message can briefly be classified into the following:
Read request message
Write request message
Request message (transmitted
from a high-level computer)
Response message (transmitted
from this product)
Receipt acknowledgement and data
response
Write complete response
Reception error and error description
response
：
Response when a normal "request message" is received
：
When a received "request message" contains an error
Store complete response
Store request message
■
In case of TOHO Protocol, all codes (except for BCC) will be expressed in ASCII code.
■
In case of MODBUS RTU, all codes will be expressed in binary code.
■
In case of MODBUS ASCII, all codes will be expressed in ASCII code.
■
To code the program for the upper computer, see “
,
and
Timing of Transmission
See
and
Request Interval
