Operating instructions

Introduction To Programming

By inserting the implied keyword in RES:LEV .5; you allowed the parser to interpret the (;) as a command to move back to

the branch containing RANG and TLEV. Without LEV in the command, the parser would "find" only RES, CURR, STAT

or other root-level commands.

HPSL Queries

You can program more than one query in a single line such as:

CURR?;RES?;VOLT? Return present values of programmed current, resistance, and voltage ,

However, observe the following precautions:

■ You must read back the results of the queries before sending another command line to the electronic load. Otherwise, a

Query Interrupted error will occur and the returned data will be lost.

■ Multiple queries must be separated by semicolons and some controllers may have problems interpreting this format. In

this case, you must enter each query and its corresponding readback on a separate line.

HPSL Compatibility

The SOURce Implied Keyword

Referring to Figure 4-2 in the Language Dictionary, note that several of the Channel-Specific branches include the implied

keyword [SOURce]. It is there to make electronic load programs compatible with other HPSL devices. Although the

electronic load will accept it, you can omit [SOURce] and consider the Channel-Specific branch as connected directly to the

root.

Aliases

Looking at Figure 4-2 you will notice that some electronic load commands will accept two keywords that perform the

identical function. For example:

MODE|FUNCtion Examples of two commands that do the same thing

INPut|OUTPut

CHANnel|INSTrument

These alternate keywords are called "aliases" and are supported by the electronic load in order to make it compatible with

other HPSL instruments.

Value Coupling

When you program, you must be aware of the effect known as value coupling. Value coupling results when a command

directed toward one parameter changes the value of another parameter. For example, the CURRent branch includes the

following keywords:

Command

CURRent[:LEVel][:IMMediate]

CURRent:RANGe

CURRent:TLEVel

There is value coupling among the RANge, LEVel, and TLEVel commands. If a previously programmed LEVel value is

outside a particular range, then changing to that range will affect the value of LEVel. There are several instances of value

coupling among the electronic load commands and you should always check a command’s description in the Language

Dictionary to determine if it is value coupled to another command.