Yokogawa PR300 Power and Energy Meter - Manual (Page 64)

<Toc> <Ind> <4. PC Link Communication Protocol>
4-3
IM 77C01E01-10E
(8) ETX (End of Text)
This control code indicates the end of a command string. The ASCII code is 03 in
hexadecimal.
(9) CR (Carriage Return)
This control code indicates the end of a command. The ASCII code is 0D in hexadeci-
mal.
NOTE
The control codes “STX”, “ETX”, and “CR” are essential for commands when you create a
communication program for PC link communication. Omission of any of them or incorrect
order of them results in communication failure.
4.1.2 Configuration of Response
Responses from the PR300 with respect to a command sent from the higher-level device
consist of the elements shown below, which differ depending on the condition of communi-
cation; normal or failure.
1) Normal Communication
When communication completes normally, the PR300 returns a character string “OK” and
data corresponding to a command.
No parameter data area for write command.
Number
of Bytes
Variable length 1 2 2 2 2 1 1
Element STX Station
number
(ST-NO)
CPU
number
01
OK Parameter data Checksum ETX CR
2) In the Event of Failure
If communication does not complete normally, the PR300 returns a character string “ER”
and error code (EC1 and EC2). (See subsection 4.1.3, “Response Error Codes”.)
• No response is made in case of an error in station number specification or CPU
number specification.
• If a PR300 cannot receive ETX in a command, response may not be made.
Note: As a countermeasure, provide a timeout process in the communication functions of the higher-level device or in
communication programs.
Number
of Bytes
1 2 2 2 2 2 3 2 1 1
Element STX ER EC1 EC2 Command Checksum ETX CR Station
number
(ST-NO)
CPU
number
01