Measurement Computing GPIB-488 - Manual (Page 49)

Chapter 3 GPIB 488.1 Library Reference
Programming Reference Manual 3-36 GPIB-488
IBRDA
Reads data asynchronously from a device/interface board into a string.
Syntax
C ibrda (int boarddev, char buf[], unsigned long
bytecount)
Parameters
boarddev is an integer containing the device/board handle.
buf is the storage buffer for the data. Up to 4 gigabytes-1 (2 32 -1 bytes) can be stored. String
size may be limited by the language you are using. Check documentation for your language.
bytecount specifies the maximum number of bytes to read.
Returns
ibsta will contain a 16-bit status word as described in Appendix B, IBSTA .
iberr will contain an error code of the first error detected, if an error occurred. An EADR
results if the specified GPIB board is an Active Controller but has not been addressed to listen.
An
EABO error results if a timeout occurs.
ibcnt , ibcntl will contain the number of bytes that were read. ibcnt is a 16-bit integer.
ibcntl is a 32-bit integer. If the requested count was greater than 64 K, use ibcntl instead
of ibcnt .
Usage Notes
Asynchronous I/O is not explicitly supported and will be treated as synchronous.
Example
In this example, ibwrt sends the command " DUMP " to a device. The device responds by
sending back a large block of data. ibrda begins a transfer of 5000 bytes in the background
and the program continues on into the WHILE loop. The WHILE loop calls ibwait with
MASK set to 0 to update IBSTA . The WHILE loop checks IBSTA to see if ibrda has
completed, or if an error has occurred. The program may do anything else within the WHILE
loop except make other GPIB I/O calls.
C char *readbuffer[5000];
ibwrt (device, "DUMP");
ibrda (device, readbuffer, 5000);
while ( (ibsta & CMPL+ERR) == 0)
ibwait (device, 0)