Lika EMC58 MT, User Manual

Page: 41 / 104

EM58 – HS58 - HM58 MODBUS TCP/IP
[04] = number of bytes (2 bytes for each register)
[00][00] = value of register 105, 00 00 hex = 0 dec
[05][DC] = value of register 106, 05 DC hex = 1500 dec
04 Read Input Registers
FC = 04 (0004 hex)
This function code is used to READ from 1 to 125 contiguous Input Registers (3X
Reference Addresses) in a remote device; in other words, it allows to read some
results values and state / alarm messages in a remote device. The Request PDU
specifies the starting register address and the number of registers. In the PDU
registers are addressed starting at zero. Therefore input registers numbered 1-16
are addressed as 0-15.
The register data in the response message are packed as two bytes per register,
with the binary contents right justified within each byte. For each register, the
first byte contains the high order bits (msb) and the second contains the low
order bits (lsb).
For the complete list of the input registers accessible using the
04 Read Input
Registers function code please refer to the “7.1.2 Input Register parameters”
section on page 68.
Request PDU
Function code 1 byte 0004 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 0004 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
0084 hex (=0004 hex +
0080 hex)
Exception code 1 byte 01 or 02 or 03 or 04
MAN EM58_HS58_HM58 MT E 1.1.odt MODBUS® TCP/IP interface 41 of 104