Keithley 708A Instruction Manual Download

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IEEE-488 Programming

5-5

5.4

Interface function codes

The interface function codes, which are part of the IEEE-
488 standards, define an instrument's ability to support
various interface functions. They should not be confused
with programming commands found elsewhere in this
manual. Interface function codes for the Model 708A are
listed in Table 5-3. The codes define Model 708A
capabilities as follows:

SH1 (Source Handshake)

— SH1 defines the ability of the

Model 708A to properly handshake data or command bytes
when the unit is a source.

AH1 (Acceptor Handshake)

— AH1 defines the ability of

the Model 708A to properly handshake the bus when it is an
acceptor of data or commands.

T6 (Talker)

— The ability of the Model 708A to send data

over the bus to other devices is defined by the T6 function.
Model 708A talker capabilities exist only after the instru-
ment has been addressed to talk. T6 means that the Model
708A is a basic talker, has serial poll capabilities, and is
unaddressed to talk when it receives its own listen address.

TE0 (Extended Talker)

— The Model 708A does not have

extended talker capabilities.

L4 (Listener)

— The L4 function defines the ability of the

Model 708A to receive device-dependent data over the bus.
Listener capabilities exist only after the instrument has been
addressed to listen. L4 means that the Model 708A is a basic
listener and is unaddressed to listen when it receives its own
talk address.

LE0 (Extended Listener)

— The Model 708A does not have

extended listener capabilities.

SR1 (Service Request)

— The SR1 function defines the

ability of the Model 708A to request service from the
controller.

RL1 (Remote Local)

— The RL1 function defines the capa-

bilities of the Model 708A to be placed in the remote or local
states.

PP0 (Parallel Poll)

— PP0 means that the Model 708A does

not have parallel polling capabilities.

DC1 (Device Clear)

— The DC1 function defines the ability

of the Model 708A to be cleared (initialized).

DT1 (Device Trigger)

— The ability for the Model 708A to

have setups triggered is defined by the DT1 function.

C0 (Controller)

— The Model 708A has no controller

capabilities.

E1 (Bus Driver Type)

— The Model 708A has open-

collector bus drivers.

5.5

Primary address programming

The Model 708A must receive a listen command before it
responds to addressed commands. Similarly, the unit must
receive a talk command before it transmits its data. The
Model 708A is shipped from the factory with a primary
address set at 18. The programming examples included in
this manual assume the address is 18.

The primary address may be set to any value between 0 and
30 (between 30 and 60 for a master unit) as long as address
conflicts with other instruments and the bus controller are
avoided. Actual master unit addresses (for programming)
will be 30 less than the address set on the Model 708A. Note
that controllers are also given a primary address, so be sure
not to use this address. Controller addresses are usually 0 or
21, but consult the controller's instruction manual for details.
Make sure the primary address you choose corresponds with
the value specified as part of the controller's programming
language.

Two rotary switches on the rear panel of the Model 708A are
used to set the IEEE-488 address. One switch is used to set
each digit of the unit's address. A leading zero is required for
addresses 0 through 9.

Table 5-3

Model 708A interface function codes

Code

Interface function

SH1
AH1
T6

TE0
L4

LE0
SR1
RL1
PP0
DC1
DT1
C0
E1

Source Handshake capability.
Acceptor Handshake capability.
Talker (basic talker, serial poll, unaddressed to
talk on MLA

No Extended Talker capabilities.
Listener (basic listener, unaddressed to listen on
MTA

No Extended Listener capabilities.
Service Request capability.
Remote Local capability.
No Parallel Poll capability.
Device Clear capability.
Device Trigger capability.
No Controller capability.
Open-collector bus drivers.

MLA – My Listen Address.

MTA – My Talk Address

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