User`s manual

Chapter 6 185
Advanced Operations
Instrument Initialization
Selected Device Clear (SDC) HP-IB Bus Command
The Selected Device Clear (SDC) Reset is accomplished by sending the
SDC message to the Test Set through HP-IB. The Test Set responds to
the Selected Device Clear (SDC) and the Device Clear (DCL) bus
commands equally. Refer to the “Device Clear (DCL) HP-IB Bus
Command” on page 184 for a description of the effects of the SDC
Reset.
Interface Clear (IFC) HP-IB Bus Command
The Interface Clear (IFC) Reset is accomplished by having the Active
Controller send the ABORT message to the HP-IB bus (ABORT
message = IFC bus control line TRUE for 100 ms).
The IFC bus command unconditionally terminates all HP-IB bus
activity and the Test Set is unaddressed.
The IFC bus command has no effect on the I/O CONFIGURE,
INSTRUMENT CONFIGURE, PRINTER CONFIGURE, SOFTWARE
MENU or TESTS (Execution Conditions, External Devices, Printer
Setup) screens.
Other operational characteristics are also affected by the IFC bus
command as follows:
• The Power-up self-test diagnostics are not performed.
• The HP-IB interface is not reset (any pending Service Request is not
cleared).
• The Contents of the SAVE/RECALL registers are not affected.
• Measurement triggering is not affected.
• Calibration data is not affected.
• All Enable registers are unaffected: Service Request, Standard
Event, Hardware #1, Hardware #2, Operation, Calibration, and
Questionable Data/Signal.
• All Negative Transition Filter registers are unaffected: Hardware
#1, Hardware #2, Operation, Calibration, and Questionable
Data/Signa.l
• All Positive Transition Filter registers are unaffected: Hardware #1,
Hardware #2, Operation, Calibration, and Questionable
Data/Signal.
• The contents of the RAM are unaffected.
• The contents of the Error Queue are unaffected.
• The contents of the Output Queue are unaffected.
• The state of the Test Set display screen is not affected