Omron SYSDRIVE 3G3MV A2002, Руководство пользователя

Страница: 206 / 348

7-12
·
The following three functions codes are available.
Function code Command name Description
03 Hex Data read Reads the data of the specified register number.
Consecutive data of a maximum of 16 words (32
bytes) can be read.
08 Hex Loop-back test The DSR message is returned as a response.
This command is used for checking the status of
communications.
10 Hex Data write The attached data in the format is written to the
specified register number. Consecutive data of a
maximum of 16 words (32 bytes) can be written.
Note 1. Do not use any code other than the above, otherwise the Inverter will detect a
communications error and return an error message.
Note 2. The Inverter uses the same function code for the response. If an error occurs,
however, the MSB of the function code will be set to 1. For example, if an error
occurs in a DSR message with function code 03, the function code of the
response will be 83.
H
Communications Data
·
Communications data is attached to the command. The contents and its arrangement
of communications data vary with the function code. For details, refer to
7-3 DSR Mes-
sage and Response .
H
Error Check
·
The CRC-16 check code is the remainder (16 bits) when all of the message blocks
from the Slave address to the final communications data are connected in series, as
shown in the following diagram, and this data is divided by a fixed 17-digit binary num-
ber (1 1000 0000 0000 0101).
Note 1.
Normally “0” is used as the initial value for CRC-16
calculations, but “--1” (16 bits all “1”) is used here.
Note 2.
The CRC-16 code is calculated with the LSB of the
Slave address handled as the MSB, and the final
MSB of the communications data handled as the
LSB.
Note 3.
Calculate the CRC-16 code for responses from the
Slave as well, and compare it with the CRC-16
code in the response message.
8 bits
The LSB of the Slave address is handled
as the MSB in CRC-16 calculation.
Slave address
Function code
Start of communications data
End of communications data
Communications Chapter 7