Kramer Electronics VP-23RC user manual Communication Protocol, Protocol Definitions

Communication Protocol

13 Communication Protocol

This protocol, which enables RS-232 communication between the VP-23RCand the PC, uses 4 bytes of information, and data is at 9600 baud, no parity, 8 data bits and 1 stop bit.

Table 18: Protocol Definitions

	MSB											LSB
		DESTINATION					INSTRUCTION
0		D		N5	N4	N3		N2		N1		N0
7		6		5	4	3		2		1		0
1st byte
									INPUT
1		0		0	0	0		I2		I1		I0
7		6		5	4	3		2		1		0
2nd byte
											OUTPUT
	1	0		0	0	0		0		O1		O0
7		6		5	4	3		2		1		0
3rd byte
							MACHINE NUMBER
	1	0		0	0	M3		M2		M1		M0
7		6		5	4	3		2		1		0
4th byte
1st BYTE:			Bit 7 ± Defined as 0.
			D ± ª DESTINATION BITº .
			This bit is always low, when sending from the PC to the switchers, and high for information sent
			to the PC.
			N5…N0 ± ª INSTRUCTIONº .

These 6 bits define the function that is to be performed by the switcher(s). 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 ± ª INPUTº .

For disconnect, set as 0. For other operations, these bits are defined according to Table 19.

3rd BYTE:	Bit 7 ± defined as 1.
	Bits 2-6 defined as 0.
	O1, O0 ± ª OUTPUTº

For operations, these bits are defined according to Table 19.

4th BYTE:Bit 7 ± Defined as 1. Bits 3-6 Defined as 0.

M3… M0 ± ª MACHINE NUMBERº .

MACHINE NUMBER = (DIPSWITCH CODE) + 1.

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