A parallel poll is the fastest way of determining the requesting device. Each device must first be programmed to respond to a parallel poll request on a unique data line (DIO1 - DIO8). For example,
PPOLL CONFIGURE 705;11
configures device 5 to respond by placing a 1 on data line DIO4. Bit 3 determines the logic sense of the data line when the device needs service. The data line to use is determined by bits 0-2, offset by one. A value of 3 means use data line DIO4.
To disable a device from responding to a parallel poll use the following commands.
PPOLL UNCONFIGURE 705 !Disables Device 5
PPOLL UNCONFIGURE 7 !Disables All Devices
To conduct the parallel poll the PPOLL function is used as follows:
Pstatus = PPOLL(7) !Parallel Poll Bus
After the parallel poll the variable Pstatus contains the value of the 8 data lines as set by the devices that have been configured to respond to the parallel poll.
