Agilent Technologies 664xA, 665xA, 667xA, 668xA, AGILENT Model 6653A: 3145A-00551, Model 6641A: 3217A-00111, Model 6645A: 3215A-00111, Model 6651A: 3130A-00171, Model 6652A: 3201A-00381, Model 6654A: 3148A-00391, Model 6655A: 3152A-00176, Model 6671A: 3129A-00218, Model 6672A: 3138A-00101, Model 6673A: 3138A-00101, Model 6674A: 3133A-00161, Model 6675A: 3138A-00101, Model 6680A: 3302A-00101, Model 6681A: 3250A-00101, Model 6682A: 3339A-00101, Model 6683A: 3339A-00161, Model 6684A: 3339A-00101

120 Digital Port Functions

In Figure D-2, the INH input is connected to a switch that shorts pin 3 to pin 4 whenever it is necessary to externally disable

the output of the supply. This will activate the remote inhibit (RI) fault protection circuit, causing the front panel Prot

annunciator to come on. It also sets the RI event bit in the supply’s Questionable Status Event register (see "Chapter 4 -

Status Reporting" in the Programming Guide). To re-enable the supply after it has been disabled by the INH input, first

open the connection between pins 3 and 4. Then clear the protection circuit either from the front panel (see "Chapter 5 -

Front Panel Operation" in this guide) or over the GPIB (see the Programming Guide).

GPIB

Figure D-2. Example of Inhibit Input

In Figure D-3A, the FLT output is connected to a relay driver circuit that energizes a relay whenever a fault condition

occurs in the power supply. The relay can be used to physically disconnect the output of the power supply from the load.

The FLT output is generated by the logical ORing of the power supply’s Operation, Questionable, and Event status summary

bits (see "Chapter 4 - Status Reporting” in the Programming Guide). You can cause one or more events to activate the FLT

output by enabling the appropriate events in these status registers. The fault condition is cleared by first removing the cause

of the fault and then reading the appropriate status event register(s).

In Figure D-3B, the FLT output of one supply is connected to the INH input of another supply. Although only two supplies

are shown, it is possible to chain other supplies with this arrangement. A fault condition in any one of the power supplies

will disable all of them without intervention either by the controller or external circuitry. The controller can be made aware

of the fault via a service request (SRQ) generated by the Questionable Status summary bit (see "Chapter 4 - Status

Reporting" in the Programming Guide).

Note The INH input cannot be used to disable outputs set from the external voltage programming port.