The Gpib-1014P As Gpib Controller; Becoming Controller-In-Charge (Cic) And Active Controller - National Instruments Corporation GPIB-1014P User Manual

Programming Considerations
A typical programmed initialization sequence for the GPIB-1014P might include the following
steps:
1.Set pon by issuing the Chip Reset auxiliary command to place the GPIB-1014P in a known,
quiescent state.
2.Set or clear the desired interrupt enable bits in Interrupt Mask Register 1 (IMR1) and Interrupt
Mask Register 2 (IMR2) of the TLC.
3.Load the TLC primary GPIB address in Address Register 0 (ADR0) and Address Register 1
(ADR1).
4.Enable or disable the GPIB Talker and Listener functions and addressing mode using the ADMR.
5.Load the Serial Poll response in the SPMR.
6.Load the Parallel Poll response in the Parallel Poll Register (PPR) if local configuration is used. If
using remote configuration, clear the PPR.
7.Clear power on (pon) by issuing the Immediate Execute pon auxiliary command to the TLC to
bring TLC on-line.
8.Execute the desired TLC auxiliary commands.

The GPIB-1014P as GPIB Controller

The GPIB-1014P Controller function is generally in one of two modes: idle or in charge. When in
charge, the Controller function is either active (asserting ATN) or standby (not asserting ATN). The
following paragraphs discuss the various transitions between these two modes.

Becoming Controller-In-Charge (CIC) and Active Controller

The TLC can become CIC either by being the System Controller and taking control (by issuing the
Set IFC auxiliary command) or by being passed control of the GPIB from the current Active
Controller.
To take control, issue the Set IFC auxiliary command, wait for a minimum of 100 µsec, and then
issue the Clear IFC auxiliary command. The ensuing GPIB IFC message initializes the GPIB
interface functions of all devices on the bus. As soon as any existing CIC goes to idle (dropping
ATN if it was active) the TLC becomes CIC and Active Controller and asserts the GPIB ATN line.
In addition to asserting IFC, the Set IFC auxiliary command also causes the GPIB transceivers for
IFC* and REN* to be configured as GPIB line drivers, thus allowing the IFC and REN lines from
the GPIB-1014P to be driven to the GPIB. The transceivers remain configured as drivers until a
system reset is received or the Disable System control auxiliary command is issued, which causes
the transceivers to be reconfigured as receivers. If the GPIB-1014P is not the System Controller,
the initialization sequence should include issuing the Disable System Control auxiliary command to
ensure that the transceivers are configured as receivers.
GPIB-1014P User Manual 5-2 © National Instruments Corporation
Section Five