Modbus Communication Standards; Table 37 . Request To Read Coils; Table 38. Request To Read Discrete Inputs; Table 39. Request To Read Holding Registers - Eaton PowerXL DG1 Series VFD Communications Manual

Modbus TCP On-Board Communications

Modbus Communication Standards

Example of the request to read coils 2000–2003 from Slave
device 18.
Table 37. Request to Read Coils
Item Code
Slave address 0x12
Function code 0x01
Start address High 0x07
Start address Low 0xD0
Number of coils High 0x00
Number of coils Low 0x03
CRC High 0x7E
CRC Low 0x25
Example of the request to read Discrete Inputs 2000–2003
from Slave device 18.

Table 38. Request to Read Discrete Inputs

Item Code
Slave address 0x12
Function code 0x02
Start address High 0x07
Start address Low 0xD0
Number of Discrete 0x00
Inputs High
Number of Discrete 0x03
Inputs Low
CRC High 0x3A
CRC Low 0x25
Example of the request to read Holding Registers 2000–2003
from Slave device 18.

Table 39. Request to Read Holding Registers

Item Code
Slave address 0x12
Function code 0x03
Start address High 0x07
Start address Low 0xD0
Number of Holding 0x00
Registers High
Number of Holding 0x03
Registers Low
CRC High 0x07
CRC Low 0xE5
24 PowerXL DG1 Series VFD MN040010EN—May 2014 www.eaton.com
Description
Starting address 0x07D0 hex (= 2000)
Number of coils 0x0003 hex (= 3)
Description
Starting address 0x07D0 hex (= 2000)
Number of Discrete Inputs
0x0003 hex (= 3)
Description
Starting address 0x07D0 hex (= 2000)
Number of Holding Registers
0x0003 hex (= 3)
Example of the request to read Input Registers 2000–2003
from Slave device 18.

Table 40. Request to Read Input Registers

Item Code
Slave address 0x12
Function code 0x04
Start address High 0x07
Start address Low 0xD0
Number of Input 0x00
Registers High
Number of Input 0x03
Registers Low
CRC High 0xB2
CRC Low 0x25
Example of the request to read exception status from Slave
device 18.

Table 41. Request to Read Exception Status

Item Code
Slave address 0x12
Function code 0x07
CRC High 4C
CRC Low D2
Example of Read Diagnostics from Slave address 18.

Table 42. Read Diagnostics

Item Code
Slave address 0x12
Function code 0x08
Sub function High 0x00
Sub function Low 0x00
Data High 0xA5
Data Low 0xA5
CRC High 0x59
CRC Low 0x83
Description
Starting address 0x07D0 hex (= 2000)
Number of Input Registers
0x0003 hex (= 3)
Description
Description
Sub function code 0x0000 (= 0)
Note. Only support sub function code
0x0000
Data 0xA5A5 (= 42405)