HP (Hewlett-Packard) 6621A Power Supply User Manual


 
Remote Operation 61
5
Remote Operation
Introduction
Chapter 3 introduced you to the basics of remote operation and provided a few simple examples using a Series 200
computer as the HP-IB controller. This chapter contains all the information required to control your power supply
remotely and discusses in greater detail how each of the commands can be implemented. The material covered is intended
for any controller capable of using the HP-IB interface functions mentioned in Interface Function, on this page.
Four major sub-sections are discussed. These are:
1. HP-IB Operation
2. Programming Syntax
3. Initial Conditions
4. Power Supply Commands
The HP-IB section briefly describes the HP-IB interface functions to get you acquainted with remote programming using
the HP-IB. Under Programming Syntax, the syntax of all commands, the numeric data formats and the programmable
ranges for all models are given. Initial Conditions highlights the initial values of all the parameters at power-on. Power
Supply Commands will describe all the commands which can be used to program the supply's functions including status
reporting, error handling, protection features, and voltage and current programming. The power supply commands are
summarized in Appendix C.
The examples are written in a generic form to make adaptation to your controller easy. You should be familiar with the
use of your controller and its instruction set and how the power supply commands can be incorporated in your controller
commands. If you are not familiar with the operation of the power supply, you are advised to read through Chapters 2
through 4 first.
HP-IB Operation
Interface Function
Remote control is implemented by the HP-IB. It enables instructions to be sent from an external computer equipped with
an HP-IB interface. The power supply implements the following IEEE-488 Interface Functions:
SH1- Source Handshake
SR1 - Service Request
AH1 - Acceptor Handshake
RL1 - Remote/Local
T6 - Talker
PP1 - Parallel Poll
L4- Listener
DC1 - Device Clear
The source handshake, acceptor handshake, talker and listener functions are implemented by the interface circuits of the
power supply and the controller. The ADDR annunciator indicates when the power supply is addressed to listen or talk.
(The talker function includes the Serial Poll, see page 62).
Service Request. This is a message which can be initiated by the power supply to request service from the controller.
When the supply is requesting service, it asserts the service request (SRQ) line on the HP-IB to interrupt the controller