bit
7
6
5
4
3
2
1
0
Coil #
9
8
7
6
5
4
3
2
Value
1
1
0
0
1
1
0
1
2
nd
Byte of Response Word
bit
15
14
13
12
11
10
9
8
Coil #
X
X
X
X
13
12
11
10
Value
0
0
0
0
1
1
0
0
Note: bits in the response marked 'X' are not valid coil response data, but are instead 0's that fill the
remainder of the byte
As a result, the Galil master's would have the following information stored in it's arrays:
array[0]=205
array[1]=12
Function Code 2 ($02)
Assume the status digital inputs on the Galil slave in descending order from 15-0 are as follows:
0111001100110111
And that the command issued from the Galil Master is MBm=,2,2,12,array[]
The Modbus request and response packets would form as follows:
Master Request
Slave Response
Field Name
Hex
Field Name
Hex
Function
$02
Function
$02
Starting Address High
$00
Byte Count
$02
Starting Address Low
$02
Inputs Status 9-2
$CD
Quantity of Inputs High
$00
Inputs Status 13-10
$0C
Quantity of Inputs Low
$0C
1
st
Byte of Response Word
bit
7
6
5
4
3
2
1
0
Input #
9
8
7
6
5
4
3
2
Value
1
1
0
0
1
1
0
1
2
nd
Byte of Response Word
bit
15
14
13
12
11
10
9
8
Input #
X
X
X
X
13
12
11
10
Value
0
0
0
0
1
1
0
1
Note: bits in the response marked 'X' are not valid input response data, but are instead 0's that fill the
remainder of the byte. Inputs report back a 0 when active and a 1 when inactive
As a result, the Galil master's would have the following information stored in it's arrays:
array[0]=205
array[1]=12
Chapter 3 Communication ▫ 32 RIO-47xxx Rev. 1.0r
