Toshiba AR-B1375 Manuale Utente

AR-B1375/AR-B1376 User’s Guide

11-1

11. PROGRAMMING RS-485 & INDEX

11.1 PROGRAMMING RS-485

The majority communicative operation of the RS-485 is in the same of the RS-232. When the RS-485 proceeds
the transmission which needs control the TXC signal, and the installing steps are as follows:

Step 1:

Enable TXC

Step 2:

Send out data

Step 3:

Waiting for data empty

Step 4:

Disable TXC

NOTE:

Please refer to the section of the “Serial Port” in the chapter “System Control” for the detail description of

the COM port’s register.

(1) Initialize COM port

Step 1:

Initialize COM port in the receiver interrupt mode, and /or transmitter interrupt mode. (All of the
communication protocol buses of the RS-485 are in the same.)

Step 2:

Disable TXC (transmitter control), the bit 0 of the address of offset+4 just sets “0”.

NOTE:

Control the AR-B1375/AR-B1376 CPU card’s DTR signal to the RS-485’s TXC communication.

(2) Send out one character (Transmit)

Step 1:

Enable TXC signal, and the bit 0 of the address of offset+4 just sets “1”.

Step 2:

Send out the data. (Write this character to the offset+0 of the current COM port address)

Step 3:

Wait for the buffer’s data empty. Check transmitter holding register (THRE, bit 5 of the address of
offset+5), and transmitter shift register (TSRE, bit 6 of the address of offset+5) are all sets must be
“0”.

Step 4:

Disabled TXC signal, and the bit 0 of the address of offset+4 sets “0”

(3) Send out one block data (Transmit – the data more than two characters)

Step 1:

Enable TXC signal, and the bit 0 of the address of offset+4 just sets “1”.

Step 2:

Send out the data. (Write all data to the offset+0 of the current COM port address)

Step 3:

Step 4:

Disabled TXC signal, and the bit 0 of the address of offset+4 sets “0”

(4) Receive data

The RS-485’s operation of receiving data is in the same of the RS-232’s.