Omega OMB-PER-488/W95, User Manual

Page: 111 / 144

Personal488 User's Manual For Windows 95 and Windows NT API Command Reference 105
SPollList
Syntax
INT WINAPI SPollList(DevHandlePT dhList, LPBYTE result, BYTE
flag);
dhList
is a pointer to a list of external devices.
result is an array that is filled in with the Serial Poll results of the corresponding external
devices.
flag refers to either ALL , WHILE_SRQ , or UNTIL_RSV .
Returns
-1 if error
Mode
*CA
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
untilflag
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
untilflag
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
untilflag
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.