ibrsp — read status byte / serial poll (device)
#include <gpib/ib.h>
int ibrsp( | ud, | |
result) ; |
int ud
;char *result
; ibrsp() obtains the status byte from the device specified
by ud
. The status byte is stored in the
location specified by result
.
If automatic serial polling is enabled on the board controlling
the device, the status byte is automatically read and queued
whenever the device requests service. If the status byte queue
is not empty ibrsp()
obtains the status
byte information from the queue. If the queue is empty the
status byte is obtained by serial polling the
device. Automatic serial polling is controlled with
ibconfig().
The contents of the status byte returned
in result
are device specific. Refer to
the device manufacturer's documentation for details. For
devices conforming to the IEEE488.1 or 2 specification the
bits defined in the table below are available if enabled in
the device's Status Byte Enable register.
constant | value | description |
---|---|---|
IbStbRQS | 0x40 | The request service bit is set when device asserts RQS. It is cleared by serial polling the device. Supported by devices conforming to IEEE 488.1 or IEEE 488.2. |
IbStbESB | 0x20 | The event-status bit is set when there are one or more bits set in the device's Standard Event Status Register. It is cleared by reading the Standard Event Status Register. For devices conforming to IEEE 488.2 only. |
IbStbMAV | 0x10 | The message available bit indicates whether or not the device's data output queue is empty. Whenever the device has data available, this bit will be set. It is cleared when the output queue is empty. The queue is emptied by reading data from the device with ibrd() for example. For devices conforming to IEEE 488.2 only. |
The value of ibsta is returned.