Control Functions
PSI BOX PLUS+ Reference
PPC.
Sends Parallel Poll Configure.
_____
__________________________
Purpose.
The addressed command Parallel Poll Configure is
__________
sent to the IEEE bus.
This command is used as part of a sequence to allow the
addressed listener to be assigned a data line for response to the
parallel poll command.
The PSI BOX asserts ATN and becomes the active
controller, then the IEEE command PPC, hex 05h decimal 5, is
sent over the IEEE bus. After the command has been sent the
ATN remains true, PSI BOX is the active controller.
The PPC command must be followed by a PPE command
or a PPD command. The PPE command is used to tell the
addressed listener which particular data line it is to use when
responding to a parallel poll, the PPE command also tells the
addressed device whether to assert the line when it requires
service or to assert the line when it does not require service.
The PPD command is used to prevent the addressed device
from responding to parallel polls. The previously assigned data
lines is remembered.
The PPC command has been included for completeness
only, it is advised that the CONFIGURE or DISABLE
commands be used to configure a device for Parallel Poll since
both these commands automatically send the PPC command.
The PPC command can also be sent by using CMD 5 or CMD
133
Format.
PPC
_________
Params.
None.
_________
Returns.
None.
__________
Example.
________
_
BUS PPC
recommended sequence (if not using CONFIGURE)
BUS UNT UNL LISTEN 1 PPC PPE 5 UNL
Chapter 8
Page 127
