VP-23 Communication Protocol
9
8 VP-23 Communication Protocol
Communication with the
VP-23
uses four bytes of information as defined below.
Data is transferred at 9600 baud with no parity, 8 data bits and 1 stop bit.
(VER-1.0)
Table 5: Protocol Definitions
1st byte
Destination
INSTRUCTION
0
D
N5
N4
N3
N2
N1
N0
7
6
5
4
3
2
1
0
MSB
LSB
2nd byte
INPUT
1
0
0
0
0
I2
I1
I0
7
6
5
4
3
2
1
0
3rd byte
OUTPUT
1
0
0
0
0
0
O1
O0
7
6
5
4
3
2
1
0
4th byte
Machine Number
1
0
0
0
M3
M2
M1
M0
7
6
5
4
3
2
1
0
1st BYTE: Bit 7 – Defined as 0.
D – “DESTINATION BIT”.
This bit is always low, when sending from the PC to the switchers, and high for information sent to the PC.
N5…N0 – “INSTRUCTION”.
The function that is to be performed by the switcher(s) is defined by this 6 bits. Similarly, if a function is performed via the
machine’s keyboard, then these bits are set with the INSTRUCTION NO, which was performed. The instruction codes are
defined according to the table below (INSTRUCTION NO. is the value to be set for N5…N0).
2nd BYTE:
Bit 7 – Defined as 1.
Bits 3 – 6 - Defined as 0.
I2… I0 – “INPUT”.
For disconnect, set as 0. For other operations, these bits are defined according to the table.
3rd BYTE:
Bit 7 – defined as 1.
Bits 2-6 defined as 0.
O1, O0 – “OUTPUT”
For operations these bits are defined according to the table.
4th BYTE:
Bit 7 – Defined as 1.
Bits 3-6 Defined as 0.
M3… M0 – “MACHINE NUMBER”.
MACHINE NUMBER = (DIPSWITCH CODE) + 1.