Quatech DS-200/300 user manual Half Duplex/Full Duplex selection, J6/J8 J6 = Serial0 J8 = Serial1

7.5 Half Duplex/Full Duplex selection

Using jumper packs J6 and J8, the channels can be configured to operate in half duplex mode. This causes the transmitters to be controlled by either the Data Terminal Ready (DTR) or the Request to Send (RTS) output from the UART. In half duplex mode, if the UART signal (DTR or RTS) is asserted (logic 1), the transmitters are enabled for both TxD and AUXOUT. At the same time, since the inverse of the transmitter enable is connected to the receiver enable, the receivers are disabled and the signal lines RXD and AUXIN enter a high-impedence state. If the signal from the UART is not asserted (logic 0), the transmitter lines enter a high-impedance state and the receivers are enabled. To operate in half-duplex DTR mode, configure J6/J8 so that pin 1 is connected to pin 4 and pin 3 is connected to pin 6. To operate in half-duplex RTS mode, configure J6/J8 so that pins 2 and 5 are connected and pins 3 and 6 are connected. The transmitters and receivers are always enabled in full duplex mode. Figure 21 shows how to select half or full duplex operation.

TXEN

TXEN

/TXEN TXEN TXEN

/TXEN	TXEN	/TXEN
	TXEN

5

2

4

1

4 5 6

1 2 3

DTR		DTR		DTR
RTS	RXEN	RTS	RXEN	RTS
					RXEN
Half-Duplex(DTR) Operation		Half-Duplex(RTS) Operation		Full-Duplex Operation

J6/J8 J6 = Serial0 J8 = Serial1

Figure 21 --- Half or Full Duplex selection on J6, J8

WARNING: When operating in half duplex mode, the transmitters must be disabled before receiving any data. Failure to do so may result in multiple active output drivers being connected together, which may cause damage to the board, the computer, and the external device.

DS-200/300 User's Manual 7-4