National Instruments GPIB-PC - Manual (Page 120)

Section Four A BASICA/QuickBASIC GPIB-PC Function Calls
©National Instruments Corp. 4A-45 GPIB-PC User Manual
BASICA/QuickBASIC BASICA/QuickBASIC
IBPPC IBPPC
Purpose: Parallel Poll Configure
Format: CALL IBPPC (BD%,V%)
Remarks: BD% specifies a device or an interface board. V% must be a
valid parallel poll enable/disable command, or zero.
When IBPPC is called and an error does not occur, the
previous value of ist is stored in IBERR% .
Device IBPPC Function:
When BD% specifies a device, the IBPPC function enables or disables
the device from responding to parallel polls.
IBPPC calls the board IBCMD function to send the following
commands:
• Listen address of the device;
• Secondary address of the device, if applicable;
• Parallel Poll Configure (PPC); and
• Parallel Poll Enable (PPE) or Disable (PPD)
Other command bytes are sent if necessary.
Each of the 16 PPE messages specifies the GPIB data line (DIO1
through DIO8) and sense (one or zero) that the device must use when
responding to the Identify (IDY) message during a parallel poll. The
assigned message is interpreted by the device along with the current
value of the individual status (ist) bit to determine if the selected line is
driven true or false. For example, if the PPE=&H64, DIO5 is driven true
if ist=0 and false if ist=1. And if PPE=&H68, DIO1 is driven true if
ist=1 and false if ist=0. Any PPD message or zero value cancels the
PPE message in effect.