Mewtocol Communication; Overview Of Mewtocol-Com (Rs485) - Panasonic kw9m User Manual

6.3 MEWTOCOL Communication

6.3.1 Overview of MEWTOCOL-COM (RS485)

◆Command and response functions
The computer sends commands (instructions) to Eco-POWER METER, and receives responses in
return. This enables the computer and Eco-POWER METER to converse with each other, so that
various kinds of information can be obtained and provided.
Computer
◆Command and response formats
(Host computer) Header
(Eco-POWER METER)
◇Control codes
Name Character
Header
Command
Normal
response
Error
response
Terminator
◇Destination and source AD (H), (L)
Two-digit decimal 01 to 99 (ASCII codes)
Command messages contain a station number for Eco-POWER METER that receives the message.
When FF (ASCII code table) is used, however, the transmission is a global transmission (sent to all
stations at once).
Note) When a global transmission is sent, no response to the command message is returned.
◇Block check code Bcc (H), (L)
Two- digit hexadecimal 00 to FF (ASCII codes)
These are codes (horizontal parity) that are used to detect errors in the transmitted data.
If "**" is entered instead of "Bcc", however, messages can be transmitted without the Bcc. In this case,
the Bcc is included with the response
◇Error code Err (H), (L)
Two- digit hexadecimal 00 to FF (ASCII codes)
These indicate the content if an error occurs.
◆Bcc （Block Check Code）
-The Bcc is a code that carries out an error check using horizontal parity, to improve the reliability of
the data being sent.
-The Bcc uses an exclusive OR from the header (%) to the final character of the text, and converts the
8- bit data into a 2-character ASCII code.
Example)
％
↑
Header
％
25H
①Commands
Eco-POWER METER
②Responses
Command message
Des-
Text
tination
ASCII code
25H
％
23H
＃
24H
＄
！ 21H
CR 0DH
0 1
＃
↑ ↑
Station No.1 Command
0 1 #
30H 31H 23H
①Takes exclusive OR
Check Termi-
code nator
Header
Explanation
Indicates the beginning of a message.
Indicates that the data comprises a command
message.
Indicates that the data comprises a normal response
message.
Indicates that the data comprises a response message
when an error occurs.
Indicates the end of a message.
R T
↑
RT 2-character
Command
R T
52H 54H
40
KW9M Eco-POWER METER
(To next command)
Check
Source Text
code
Normal response message
0 1 CR
↑
Bcc
0 1
Bcc(H)=0(30H)
Bcc(L)=1(31H)
②Converts to ASCII format
Termi-
nator