HP Water System HP VXI 사용자 설명서

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Define an SRQ handler to do the following: 

-- Read the Status Byte using ireadstb

.

  ireadstb returns the RQS 

(request for service) bit in bit 6 of the status byte.  After issuing a 
ireadstb, RQS is cleared indicating that the Service Request is being 
acknowledged.  A new SRQ will not be issued unless RQS is 
cleared.  Using *STB? will return the Master State Summary in bit 6 
and does not affect RQS.

-- Check if the MAV bit (bit 4) is set to indicate that a message is 

available. If the MAV bit is set, then a message is available and the 
SRQ handler can process the message.  In this example, the output 
queue is read using iscanf

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Enable SRQ Handler in SICL with ionsrq.

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Enable MAV bit (Message Available Bit) in the Status Byte Enable 

Register (e.g. *SRE 16).  This will cause an SRQ to arrive when there 
is a message in the output queue  (i.e. data is available to be read)  

/* status1.c * 
* The following program provides an interactive command line interface  
* to send SCPI commands to SCPI compatible instruments. 
* This utilizes the MAV bit of the Status Byte in order to determine if 
* the instrument is returning any output.   */
#include <sicl.h>
#include <stdio.h>

/* Theses are Masks for the Status Byte */
/* all bits start at bit 0 */
#define MAV_MASK 0x10      /* MAV - bit 4 */

/* This is the SRQ handler to check for Message Available (MAV) */
void srq_hdlr( INST id) {
    unsigned char stb;
    char buf[255];
    int esr;
    int errnum;
    char errmsg[100];

    /* read the status byte to determine what caused the SRQ. 

   * Note: use ireadstb instead of *STB? because you want to
   * clear RQS instead of reading the MSS bit in the status byte.*/

   ireadstb(id, &stb);

   /* check if MAV caused the SRQ */ 

 if( MAV_MASK == (stb & MAV_MASK)) 
 {

        /* message is available so read in the result. */ 

      iscanf( id, "%t", buf); 
      printf("%s", buf); 
 }

}