Lika EM58 MB, User Manual

Page: 58 / 92

ES58 • EM58 MODBUS®
Request PDU
Function code 1 byte 04 hex
Starting address 2 bytes 0000 hex to FFFF hex
Quantity of Input Registers 2 bytes 0000 hex to 007D hex
Response PDU
Function code 1 byte 04 hex
Byte count 1 byte
2 x
N*
Input register value N*
x 2 bytes
*N = Quantity of registers
Exception Response PDU
Error code 1 byte 84 hex (=04 hex + 80 hex)
Exception code 1 byte 01 or 02 or 03 or 04
Here is an example of a request to read the Current position [0001-0002
hex] parameter (input registers 2 and 3).
Request Response
Field name (Hex) Field name (Hex)
Function 04 Function 04
Starting address Hi 00 Byte count 04
Starting address Lo 01 Register 3 value Hi 00
Quantity of Input Reg. Hi 00 Register 3 value Lo 00
Quantity of Input Reg. Lo 02 Register 4 value Hi 2F
Register 4 value Lo F0
As you can see in the table, the Current position [0001-0002 hex] parameter
(input registers 2 and 3) contains the values 00 00 hex and 2F F0 hex, i.e. 12272
in decimal notation.
MAN ESx58x_EMx58x MB E 1.3 MODBUS® interface 58 of 92