Yokogawa JUXTA M Series Digital Limit Alarms MVTK Manual de usuario descargar pdf (Pagina 48)

5-2

IM 77J04J11-01E 1st Edition : 2006.08.25-00

5.1.1 Configuration of Message

Messages sent from a higher-level device to the M Series consist of the following elements.

Number of bytes in RTU mode None

Number of bytes in ASCII mode 2 2

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

Element Address

Number

(ADR)

Function CodeStart of

Message Mark

Data Error Check End of

Message Mark

None

1224n

1 1 2n 2

(1) Start of Message Mark

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

colon (:).

(2) Address Number (01 to 99)

Address numbers are used by a higher-level device to identify the M Series at the

communication destination. (Identification numbers specific to individual M Series,

which is expressed in hexadecimal in the message.)

(3) Function Code (See subsection 5.2.1, "List of Function Codes.")

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

(4) Data

This 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.

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Yokogawa JUXTA M Series Digital Limit Alarms MVTK Manual de usuario Pagina 48