Measurement Computing Personal488 rev.3.0 For DOS & Windows 3.Xi - Manual (Page 78)

II. SOFTWARE GUIDES - 8. Driver488/DRV 8E. Microsoft C
Personal488 User’s Manual, Rev. 3.0 II-63
critical error trapping is to be enabled. Only read and write commands to that handle are trapped.
Errors caused by other actions, or associated with other files are not trapped. Error trapping may only
be enabled for one file at a time.
Now, if IEEEWT signals an error by returning a -1 , we can check what happened. We first PRINTF an
error message, then we turn critical error trapping off with CRIT_OFF so that, if another critical error
occurs, we get the ABORT , RETRY or IGNORE message and know a catastrophic double error has
occurred. We then IOCTL_WT(_BREAK_) to force Driver488/DRV to listen to our next command.
The IOCTL_WT also resets the EOL OUT terminator so we can be sure that Driver488/DRV detects the
end of our commands. We next reset the EOL OUT terminator to our preferred line feed only and ask
Driver488/DRV for its status. On receiving the response, we could interpret the status and take
whatever action is appropriate. However, in this example, we just display the status. Finally, we re-
enable the critical error handler and continue with the program.
Sample Program
#include “ieeeio.h”
#include
void main (void){
int ieee
char response[256];
float voltage;
int i;
float sum;
char hundred[1700];
ieee=open(“ieee”,O_RDWR | O_BINARY);
rawmode(ieee);
ioctl_wt(ieee,"break",5);
ieeewt(“reset\r\n”);
ieeewt(“eol out lf\r\n”);
ieeewt(“eol in $0\n”);
ieeewt(“fill error\n”);
if (ieeeinit() == -1) {
printf(“Cannot initialize IEEE system.\n”);
exit(1);
}
ieeewt(“hello\n”);
ieeerd(response);
printf(“%s\n”,response);
ieeewt(“status\n”);
ieeerd(response);
printf(“%s\n”,response);
ieeewt(“output 16;F0R0X\n”);
ieeewt(“enter 16\n”);
ieeescnf(“%*4s%e”,&voltage);
printf(“The read value is %g\n”,voltage);
sum=0.0;
for (i=0; i<10; i++) {
ieeewt(“enter 16\n”);
ieeescnf(“%*4s%e”,&voltage);
sum=sum+voltage;
}
printf(“The average of 10 readings is %g\n”,sum/10.0);
ieeeprtf(“ENTER 16 #1700 BUFFER %d:%d\n”,
segment(hundred),offset(hundred));
for (i=0; i<1700; i++) putchar(hundred[i]);
ieeeprtf(“ENTER 16 #1700 BUFFER continue\n”,
segment(hundred),offset(hundred));
ieeewt(“status\n”);
ieeerd(response);
printf(“%s\n”,response);
int cklpint();
ieee_cki = cklpint;
ieee_isr = isr;
ieeewt(“arm srq\n”);