Measurement Computing Micro 488/EX rev.2.1 - Manual (Page 128)

Section 5 Command Descriptions
5.58
PPOLL
The Parallel Poll command, PPOLL, is used to request status information from
many bus devices simultaneously. If a device requires service then it will respond to a
Parallel Poll by asserting one of the eight IEEE bus data lines (DIO1 through DIO8,
with DIO1 being the least significant). In this manner, up to eight devices may
simultaneously be polled by the controller. More than one device can share any
particular DIO line. In this case it is necessary to perform further Serial Polling to
determine which device actually requires service.
Parallel polling is often used upon detection of a Service Request (SRQ), though
it may also be performed periodically by the controller. In either case, PPOLL will
respond with a number from 0 to 255 corresponding to the eight binary DIO lines.
Not every device supports parallel polling. Refer to the manufacturer's
documentation for each bus device to determine if Parallel Poll capabilities are
supported.
SYNTAX PPOLL
RESPONSE Number in the range of 0 to 255
MODE CA
BUS STATES ATN•EOI,, *EOI
EXAMPLE PRINT#1"PPOLL" Conduct a Parallel Poll
INPUT#1,PPSTAT Receive the PPOLL status
PRINT PPSTAT