Measurement Computing Personal488 rev.3.0 - Manual (Page 121)

Personal488 for Windows 95/98/Me/NT/2000 04-10-01 API Reference 6-53
SPollList
Syntax INT WINAPI SPollList(DevHandlePT devHandleList,
LPBYTE resultList, BYTE SPollFlag);
devHandleList is a pointer to a list of external devices.
resultList is an array that is filled in with the Serial Poll results of the corresponding
external devices.
SPollFlag refers to either ALL , WHILE_SRQ , or UNTIL_RSV .
Returns -1 if error
Bus States ATN
•UNL, MLA, TAG, SPE, *ATN, ATN•SPD, UNT
Example deviceList[0] = wave;
deviceList[1] = timer;
deviceList[2] = dmm;
deviceList[3] = NODEVICE;
result = SPollList(deviceList,
resultList, ALL);
Returns the Serial Poll response for a list of
device handles.
See Also SPoll, PPoll
In Active Controller mode, the SPollList (Serial Poll) command performs a Serial Poll of the bus devices
specified and responds with a number from 0 to 255 (representing the decimal equivalent of the eight-bit
device response) for each device on the list. If rsv ( DIO7 , decimal value 64 ) is set, then that device is
signaling that it requires service. The meanings of the other bits are device-specific.
Serial Polls are normally performed in response to assertion of the Service Request ( SRQ ) bus signal by
some bus device. In Active Controller mode with the interface device specified, the SPollList command
returns the internal SRQ status for each device. If the internal SRQ status is set, it usually indicates that the
SRQ line is asserted. Driver488 then returns a 64 . If it is not set, indicating that SRQ is not asserted, then
Driver488 returns a 0 . With an external device specified, SPollList returns the Serial Poll status of the
specified external device.
In Peripheral mode, the SPollList command is issued only to the interface and returns the Serial Poll
status. If rsv ( DIO7 , decimal value 64 ) is set, then Driver488 has not been Serial Polled since the last
Request command was issued. The rsv is reset whenever Driver488 is Serial Polled by the Controller.
The SPollFlag refers to either ALL , WHILE_SRQ , or UNTIL_RSV . If ALL is chosen, all the devices are
Serial Polled and their results placed into the result array. If SPollFlag is WHILE_SRQ , Driver488 Serial
Polls the devices until the SRQ bus signal becomes unasserted, and the results are put into the result array.
If SPollFlag is UNTIL_RSV , Driver488 Serial Polls the devices until the first device whose rsv bit is set,
is found and the results are put into the result array.