YASKAWA AC Drive V1000 Option SI-EM3/V - Page 26

7 Modbus TCP/IP Messaging
26 YASKAWA ELECTRIC SIEP C730600 59A V1000 Option Modbus TCP/IP Technical Manual
 Data
This field contains multiple bytes of varying length based upon the Function Code for commands and based upon the
results of the command in the response. When sent by the master, this field contains details of the command that the slave
will require to carry out the function. When sent by the slave, this field contains details of the response and sometimes
error information.
 Modbus TCP/IP Option Function Details
 03 (03 H) Read Multiple Registers
This function code is used to read the contents of a contiguous block of registers. The command specifies the starting
register and the number of registers. The normal response packs two bytes per register. For each register in the response,
the first byte contains the most significant bits and the second byte contains the least significant bits.
Table 13 Read Multiple Registers (Command)
Table 14 Read Multiple Registers (Response)
Table 15 Read Multiple Registers (Error Response)
Examples of Fault Response, Read Response, and Read Multiple Registers Command
Table 16 lists command examples to read register contents (register addresses 0020H to 0023H) from a drive with the
slave address (unit identifier) 02H.
Table 17 shows examples of responses indicating that multiple registers have been read successfully. The contents read
from 0020H are 1770H, 1770H, 0109H, and 0000H.
Table 18 shows examples of an error response when reading multiple registers. The exception code is 02H (indicating a
register number error).
Table 16 Example Read Multiple Registers Command
Description
<1> N = Quantity of Registers (range is 1 - 16)
Byte(s) Data (H)
Slave Address 1 00 to FF
Function Code 1 03
Starting Register 2 0000 to FFFF
Quantity of Registers 2 N
<1>
Description
<1> N = Quantity of Registers
Byte(s) Data (H)
Slave Address 1 00 to FF
Function Code 1 03
Number of Data Bytes 1 2 x N
<1>
Register Values N <1> x 2 Values contained in slave registers.
Description Byte(s) Data (H)
Slave Address 1 00 to FF
Error Code 1 83
Exception Code 1 See Modbus TCP/IP Exception Codes section.
Description Data (H)
Slave Address 02
Function Code 03
Starting Register
Upper 00
Lower 20
Quantity of Registers
Upper 00
Lower 04
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