HP 8920B - Page 335

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Chapter 5, Advanced Operations
Passing Control
Configuring the Test Set as the System Controller
To configure the Test Set as a System Controller, select the I/O CONFIGURE
screen, position the cursor to the Mode field using the Cursor Control knob,
highlight the Mode field by pushing the Rotary Knob, select Control from the
Choices menu. As a consequence of setting the Test Set to be the System
Controller it will also become the Active Controller. The letter C appears in the
upper-right corner of the display to indicate that the Test Set is now the Active
Controller.
If the Test Set is the only controller on the bus it must be configured as the System
Controller. If the Test Set is not the only controller on the bus, then whether or not
it is configured as the System Controller would depend upon three issues:
1. whether or not other controllers have System Controller capability
2. which controller will be the Active Controller upon power-up
3. which Controller will be monitoring the bus to determine if communications have
failed (only the System Controller can unconditionally demand control of the bus and
reset it to a known state using the IFC line)
Ensure that only one Controller connected to the bus is configured as the System
Controller or bus conflicts will occur.
When Active Controller Capability is Required
The Test Set must be the Active Controller on the bus under the following
conditions:
1. whenever the Test Set needs to control any device connected to the HP-IB bus, such as
an external disk drive, an external printer, or an external instrument
2. whenever a screen image is printed to an external HP-IB printer
3. Whenever an instrument configuration is saved or recalled from an external HP-IB disk
drive
4. Whenever running any HP 11807 Radio Test Software package which uses an external
HP-IB device such as a disk drive, a printer, or an instrument
5. Whenever running any IBASIC program which uses an external HP-IB device such as
a disk drive, a printer, or an instrument