Mewtocol Communication; Overview Of Mewtocol-Com (Rs485) - Panasonic KW9M User Manual

1.3 MEWTOCOL Communication

1.3.1 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
②Responses
◆Command and response formats
(Host computer) Header
(Eco-POWER METER)
◇Control codes
Name Character
Header
％
Command
＃
Normal
＄
response
Error
！
response
Terminator CR
◇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 Station No.1
％
25H 30H
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com
①Commands
Eco-POWER METER
Command message
Des-
Text
tination
ASCII code
Indicates the beginning of a message.
25H
Indicates that the data comprises a command
23H
message.
Indicates that the data comprises a normal response
24H
message.
Indicates that the data comprises a response message
21H
when an error occurs.
0DH Indicates the end of a message.
0 1
＃
↑ ↑
Command
0 1 #
31H 23H
①Takes exclusive OR
Check Termi-
code nator
Header Source
Explanation
R T 0 1
↑ ↑
RT 2-character
Command Bcc
R T 0 1
52H 54H
2
(To next command)
Check Termi-
Text
code nator
Normal response message
CR
Bcc(H)=0(30H)
Bcc(L)=1(31H)
②Converts to ASCII format