}
19Set COM1 port as RS485 or modem
This function call is used to set COM1 port as RS485 serial port or modem when you have the internal modem interface installed. Before you can start to use modem for communication, you must set COM1 port as modem.
Entry Parameters: | AH = 19 |
|
| AL = 0 | ; set as RS485 |
| 1 | ; set as modem |
Returned Value: | None |
|
void TC_modem_port(int status)
{
regs.h.ah= 0x19; regs.h.al= status; int86(0x21,®s,®s);
}
3.3.Host Port for Multi-point Protocol I/O (INT21H)
1C Setup multi-point address
Entry Parameters: | AH = 0x1C |
| BH = 06 |
| AL = 'A'..'Y','0'..'6' |
Returned Values: | None |
void TC_set_address(char status)
{
regs.h.ah= 0x1C; regs.h.al= status; regs.h.bh= 6; int86(0x21,®s,®s);
}
1C Set polling timeout duration
Entry Parameters: | AH = 0x1C |
| BH = 09 |
| AL = |
Returned Values: | None |
void TC_time_out(int status)
;timeout period with base timeout cycle 80ms ;timeout period is 160ms when set AL=2; AL=0 for no timeout
