Measurement-computing Personal488 rev.3.0 For DOS & Windows 3.Xi Instrukcja Użytkownika Pobierz pdf (Strona 169)

9E. C Languages II. SOFTWARE GUIDES - 9. Driver488/SUB

II-154 Personal488 User’s Manual, Rev. 3.0

External Device Initialization

Refer to the device manufacturer’s documentation on specific requirements for initializing your

IEEE 488 instrument. In the case of the ADC488, appropriate initialization involves sending it a

Clear

command and placing it into

Remote

mode:

Clear (adc) ;

Remote (adc) ;

For our hypothetical application, we also wish to have the ADC488 generate a service request should it

detect a command error. This involves sending a command string consisting of textual data to the

ADC488:

Output (adc, “M8X”) ;

We may also wish to perform other initialization and configuration. In this case, we set up the

ADC488 (

adc

) in the following configuration:

/* Setup the ADC488

Differential inputs (A0)

Scan group channel 1 (C1)

Compensated ASCII floating-point output format (G0)

Channel 1 range to +/-10V (R3)

One-shot trigger on talk (T6)

The command to perform this configuration combines the above strings and adds the

Execute

(

)

command for the ADC488:

Output (adc,”A0C1G0R3T6X”) ;

Interrupt Handling

In case we send out an invalid command, either due to a programming error or an unanticipated

condition in the equipment, Driver488/SUB will automatically notify the interrupt handling function as

established above:

Output (adc,”V13X”) ;

The interrupt handler as established above might consist of a function similar to the following:

void isr (OpaqueP param) {

int sp,

stadc,

errnum;

char errtext [64] ;

/* Print parameter passed to isr to screen */

printf (“ In intrrupt handler, param=%d\n”,param) ;

/* Check if the intrrupt was due to a Service Request */

sp=SPoll (ieee) ;

if (sp==0) {

printf (“ No SRQ detected\n”) ;

exit (1) ;

}

/* Check that the Service Request was from the ADC488 */

stadc=SPo;l (adc) ;

if ((stadc&0x40)==0) {

printf (“ Not an ADC488 SRQ.\n”) ;

exit (1) ;

}

/* Interpret the Serial Poll response */

if (stadc&0x01)

printf (“ Triggered\n”) ;

if (stadc&0x02)

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