Delta ASDA-A3 Series, Руководство пользователя

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MODBUS Communication ASDA-A3
9-4
9
9.3 MODBUS communication protocol
There are two modes of MODBUS network communication: ASCII (American Standard Code for
Information Interchange) and RTU (Remote Terminal Unit). You can set both communication
protocols (ASCII and RTU) with P3.002. The ASDA-A3 servo drive also supports these
functions: accessing data (03H), writing one character (06H), and writing multiple characters
(10H). Refer to the following descriptions.
Code description
ASCII mode:
In ASCII mode, data is transmitted in ASCII (American Standard Code for Information
Interchange) format. For instance, when transmitting “64H” between two stations (master and
slave), the master sends 36H to represent ‟6” and 34H to represent “4”.
The ASCII codes for the digits 0 to 9 and the characters A to F are as follows:
Character ‘0’ ‘1’ ‘2’ ‘3’ ‘4’ ‘5’ ‘6’ ‘7’
ASCII code 30H 31H 32H 33H 34H 35H 36H 37H
Character ‘8’ ‘9’ ‘A’ ‘B’ ‘C’ ‘D’ ‘E’ ‘F’
ASCII code 38H 39H 41H 42H 43H 44H 45H 46H
RTU mode:
Every 8-bit data frame consists of two 4-bit characters (hexadecimal). For example, if “64H” is
transmitted between two stations using RTU, it is transmitted directly, which is more efficient
than ASCII mode.
Characters are encoded into the following frames and transmitted in series. The method for
checking each type of frame is as follows.
10-bit character frame (for 7-bit character)
7N2
Start
bit
Stop
bit
Stop
bit
0 1 2 3 4 5 6
7-data bits
10-bit character frame
L H H
7E1
Start
bit
Even
Parity
Stop
bit
0 1 2 3 4 5 6
7-data bits
10-bit character frame
L H
7O1
Start
bit
Odd
Parity
Stop
bit
0 1 2 3 4 5 6
7-data bits
10-bit character frame
L H