Measurement-computing PCI-COM422/485 Manual de usuario descargar pdf (Pagina 17)

READ/WRITE

31:876543210

xxxxXxINTINTPOLINTE

The UART ports are 16C550 compatible. See any 16C550 data sheet for register functions.

AVAILABLE PORTS:

PCI-COM422/485: PORT 1

PCI-COM422/485-2: PORTS 1-2

4.2.2 PORT 1 CLOCK SELECT / INTERRUPT STATUS

BADR2 + 07 hex

READ

76543210

PORT1

TXSEL1

PORT1

TXSEL0

PORT1

CKSEL1

PORT1

CKSEL0

- - INT2 INT1

WRITE

76543210

PORT1

TXSEL1

PORT1

TXSEL0

PORT1

CKSEL1

PORT1

CKSEL0

PORT1

ECHOEN

---

INTx Interrupt status for each port. The same signals are connected to this read register for all ports.

CKSEL1:0 UART clock select. This allows for data rates to 460.8 Kbps and different data rates on

each port. These settings are per port:

CKSEL1 CKSEL0

UART CLOCK Max Data Rate

0 0 1.8432 MHz 115.2 kbps

0 1 3.6864 MHz 230.4 kbps

1 0 7.3728 MHz 460.8 kbps

TXSEL1:0 Transmit data control select. This allows for controlling the Transmit Data driver. The

default mode for RS485 is ‘Auto Enable’. This mode is recommended for all RS485 communication.

TXSEL1 TXSEL0

Transmit Control Duplex Mode

0 0 Auto Enable Half

0 1 RTS Enable Half

1 0 DTR Enable Half

1 1 Transmit ‘ON’ Full – RS422 Mode

ECHOEN 1:0 Echo enable/disable. When set low, this enables the hardware to echo the transmitted data to the

receiver. When set high, this disables the ‘Receiver Enable’ control signal on the RS485 transceiver while data is

being transmitted. Therefore, the transmitted data are not echoed to the receiver.

For TXSEL0:1 = ‘11’, ECHOEN has no function since this is full duplex mode and the transmitter and receiver are

always ‘ON’.

4.2.3 PORT 2 CLOCK SELECT / INTERRUPT STATUS

BADR3 + 07 hex

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 23 24

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