Measurement Computing Personal488 rev.3.0 For DOS & Windows 3.Xi - Manual (Page 317)

15A. Driver488/DRV Commands III. COMMAND REFERENCES - 15. Command References
III-302 Personal488 User’s Manual, Rev. 3.0
PASS CONTROL
SYNTAX PASS CONTROL addr
addr is a device address (primary with optional secondary) or the external device
name of the device to which control is passed.
RESPONSE None
MODE CA
BUS STATES ATN
•UNL, MLA, TAG, UNL, TCT, *ATN
SEE ALSO ABORT, RESET, SEND
EXAMPLE 100 PRINT#1, "PASS CONTROL 22" Control is passed to device 22.
110 PRINT#1,"STATUS" Use STATUS to check control.
120 INPUT#1,A$ Wait until we are controller again
130 IF LEFT$(A$,1)"C" THEN 110
The PASS CONTROL command allows Driver488 to give control to another controller on the bus. After
passing control, Driver488 enters the Peripheral mode. If Driver488 was the System Controller, then it
remains the System Controller, but it is no longer the Active Controller. The Controller now has
command of the bus until it passes control to another device or back to Driver488. The System
Controller can regain control of the bus at any time by issuing an
ABORT command.
PPOLL
SYNTAX PPOLL
RESPONSE Number in the range 0 to 255.
MODE CA
BUS STATES ATN
•EOI , *EOI
SEE ALSO PPOLL CONFIG, PPOLL UNCONFIG, PPOLL DISABLE, SPOLL
EXAMPLE PRINT#1,"PPOLL" Conduct a Parallel Poll
INPUT#2,PPSTAT Receive the PPOLL status
The PPOLL (Parallel Poll) command is used to request status information from many bus devices
simultaneously. If a device requires service, it responds to a Parallel Poll by asserting one of the eight
IEEE 488 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 responds with a number from 0 to 255
corresponding to the eight binary DIO lines. Refer to the manufacturer’s documentation for each
device to determine whether or not Parallel Poll capabilities are supported.
PPOLL CONFIG or PPC
SYNTAX PPOLL CONFIG addr;response or PPC addr;response
addr is a device address (primary with optional secondary) or an external device
name.
response is the decimal equivalent of the four binary bits S , P2 , P1 , and P0
where S is then Sense bit, while P2 , P1 , and P0 assign the DIO bus data line
used for the response.
RESPONSE None
MODE CA
BUS STATES ATN
•UNL, MTA, LAG, PPC
SEE ALSO PPOLL, PPOLL UNCONFIG, PPOLL DISABLE
EXAMPLE See next page.