HP 34401A, User Manual

Page: 194 / 236

printf("\nEnter command string:\n");
gets(command); strcat(command,"\n"); /* SCPI requires line feed */
if(command[0] == 0x19) send_ctlc(); /* If ^Y then send ^C */
else if(command[0] != ’q’) {
for(i=0; i<strlen(command); i++) {
/* Wait for DSR and transmitter hold register empty */
while(!(inportb(LSR) & inportb(MSR) & 0x20)) ;
outportb(THR,command[i]); /* Send character */
}
}
if(strpbrk(command,"?")) { /* If query then get response */
c = 0;
do {
while(int_buf_count && !kbhit()) {
putch(c = *int_+); int_buf_count--;
if(int_buf_out >= i INT_BUF_size) int_buf_out = int_buf;
}
if(kbhit()) {
if(getch() == 0x19) send_ctlc(); /* if ^Y then send ^C */
c = 0xa; /* Terminate loop */
}
}
while(c != 0xa);
} /* End if */
}
while(command[0] != ’q’); /* ’q’ to quit program */
outportb(IER,inportb(IER) & 0xfe); /* Disable UART interrupt */
outportb(MCR,0x1); /* Disable IRQ buffer, DTR = 1 */
/* Disable IRQ4 in 8259 interrupt controller register */
outportb(INT_con1,inportb(INT_con1) | ~IRQ4_enab);
setvect(IRQ4_int,oldvect); /* Restore old interrupt vector */
return(0);
}
RS-232 Operation Using Turbo C (continued)
Continued on next page
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6
Chapter 6 Application Programs
RS-232 Operation Using Turbo C
195