Controllerprogramming; Controller Handler Software; Interface Basic Programming Statements - Keithley 263 Instruction Manual

IEEE-488 PROGRAMMING
data. The Model 263 is shipped from the factory with a
programmed primary address of 8. Until you become
more familiar with your instrument, it is recommended
that you leave the address at this value because the pro-
gramming examples included in this manual assume that
address.
The primary address may be set to any value between 0
and 30 as long as address conflicts with other instruments
are avoided. Note that conrollers are also given a primary
address, so you must be careful not to use that address
either. Most frequently, controller addresses are set to 0
or 21, but you should consult the controller's instruction
manual for details. Whatever primary address you choose,
you must make certain that it corresponds with the value
specified as part of the controller's programming
language.
To check the present primary address or to change to a
new one, perform the following procedure:
1. Press the MENU button until the current primary ad-
dress is displayed. For example, if the instrument is set
to primary address 8, the following message will be
displayed:
IEEE 8
2. To retain the current address, press MENU until the
instrument exits the front panel program mode.
3. To change the primary address, do so using the AD-
JUST buttons and press MENU once to exit the program
mode. The new address will be stored in memory so
that the instrument will power up to that address.
Note: Each device on the bus must have a unique primary
address. Failure to observe this precaution will probably
result in erratic bus operation.
4.4 CONTROLLER PROGRAMMING
There are anumber of IEEE-488 controllers available, each
of which has its own programming language. Also, dif-
ferent instruments have differing capabilities. In this sec-
tion, we will discuss the programming language for the
HP 85 computer.
NOTE
Controller programming information for using the
IBM-PC interfaced throueh a Caoital Eauioment
Corporation (CEC) IEEE-488 inte&e is {o&ted in
Appendix D. See Appendix E for other controller
example programs.
4.4.1 Controller Handler Software
Before a specific controller can be used over the IEEE-488
bus, it must have IEEE-488 handler software installed.
With some controllers, the software is located in ROM,
and no software initialization is required on the part of
the user. With other controllers, software must be loaded
from disk or tape and be properly initialized. With the
HP-85, an additional I/O ROM that handles interface func-
tions must be installed.
Other small computers that can be used as IEEE-488 con-
trollers may have limited capabilities. With some, inter-
face programmin g functions may depend on the interface
being used. Often little software "tricks" are required to
obtain the desired results.
From the preceding discussion, the message is clear: make
sure the proper software is being used with the interface.
Often, the user may incorrectly suspect that the hardware
is causing a problem when it was the software all along.
4.4.2 Interface BASIC Programming
Statements
The programmin g instructions covered in this section use
examples written with Hewlett Packard Model 85 BASIC.
This computer was chosen for these examples because of
its versatility in controlling the IEEE-488 bus. This section
covers those statements that are essential to Model 263
operation.
A partial list of HP-85 BASIC statements is shown in Table
4-2. HE-85 BASIC statements have a one or three digit
argument that must be specified as part of the statement.
The first digit is the interface select code, which is set to
7 at the factory. The last two digits of those statements,
requiring a3digit argument, specify the primary address.
Those statements with a 3-digit argument listed in the
table show a primary address of 8 (the factory default
primary address of the Model 263). For a different address,
you would, of course, change the last two digits to the
required value. For example, to send a GTL command to
a device using a primary address of 28, the follmving state-
ment would be used: LOCAL 728.
Some of the statements have two forms; the exact con-
figuration depends on the command to be sent over the
bus. For example, CLEAR 7 sends a DCL comman d, while
CLEAR 708 sends the SDC command to a device with a
primary address of 8.
4-4