Moeller DF51 - Page 158

Serial interface (Modbus)
10/05 AWB8230-1541GB
154
Explanation of function codes
Read coil status [01
hex
]:
This function reads the status (On/Off) of the selected coils. For
example: reading input signal terminals 1 to 6 of the DF51 with
slave address 8. In this example, the inputs have the following
states.
The data range of the response contains the states of coils 7 to 14. The status is given by 17
hex
(00010111
bin
). COIL 7 is the least
significant bit (LSB)
If a read coil lies outside the specified range, the remaining bytes
to be transmitted have a zero value to indicate the out-of-range
value.
If a coil can not be given as a normal value, an exception message
(a section “Exception signal (error code)”, page 160) is
generated.
Name Function
Digital input [1] [2] [3] [4] [5] [6]
Coil status ON ON ON OFF ON OFF
Request Response
No. Name Example No. Name Example
hex hex
1 Slave address (broadcast is disabled) 08 1 Slave address 08
2 Function code 01 2 Function code 01
3
Coil start number (High byte) 00 3 Data size (in bytes) 01
4
Coil start number (Low byte) 07 4 Coil data.
Number of selected bit variables (data size)
17
5 Number of coils (High byte)
If this value is 0 or greater than 32, a fault
message with code 03
hex
is issued.
00 5 CRC-16 (High byte) 12
6
Number of coils (Low byte).
If this value is 0 or greater than 32, a fault
message with code 03
hex
is issued.
06 6 CRC-16 (Low byte) 1 A
7 CRC-16 (High byte) 0D
8 CRC-16 (Low byte) 50
Term Data
Coil number 14 13 12 11 10 9 8 7
Coil status OFF OFF OFF ON OFF ON ON ON