Energy Meter Manual

5-3

IM 77C01E01-10E

5.1.1 Configuration of Message

Messages sent from the higher-level device to the PR300 consist of the following elements.

Number of bytes

in RTU mode

None

Number of bytes

in ASCII mode

(1) (3) (4) (5)(2) (6)

Element

Station

Number

(ST-NO)

Function

Code

Start of

Message Mark

Data Error Check End of

Message Mark

None

1224n

(variable)

112n

(variable)

(1) Start of Message Mark

This mark indicates the start of a message. Note that only ASCII mode requires a

colon (:).

(2) Station Number (01 to 99)

Station numbers are used by the higher-level device to identify the PR300 at the

communication destination. (These numbers are identification numbers specific to

individual PR300, which are expressed in hexadecimal in the message.)

00: Broadcasting mode (See subsection 5.1.5, “Specifying Broadcast”)

(3) Function Code (See section 5.2, “Message and Response”)

This element specifies a command (function code) from the higher-level device.

(4) Data

This element specifies D register numbers, the number of D registers, parameter

values, or others in accordance with the function code. (It is expressed in hexadecimal

in the message.)

(5) Error Check

In RTU mode: Carried out by the cyclic redundancy check (CRC-16) system.

In ASCII mode: Carried out by the longitudinal redundancy check (LRC) system.

(6) End of Message Mark

This mark indicates the end of a message. Note that only ASCII mode requires CR +

LF.