44
Remote and Local States
Local State
When the 4300C is in the "local" state the REMOTE indicator on the front panel is extinguished and full
manual control may be performed. The user should also note that the 4300C will ignore commands from
the GPIB while in the local state.
The 4300C automatically powers-up in the local state. Other methods for placing it in the local state are
by cycling power or by sending a return to local (RTL) command over the bus. This is done in HP Basic
using the command: LOCAL 712
To ensure compatibility with all controllers, the 4300C may also be returned to the local state by sending
it the code: L
Remote State
In this state the REMOTE indicator on the front panel is illuminated and all controls on the front panel are
disabled except the power switch.
The remote state may only be entered via the bus. If the 4300C receives its listen address while the REN
line is asserted, it will enter the remote state. Placing the instrument into remote is an easy way of
verifying that all connections and address selections have been done properly. This may be accomplished
in HP Basic using the command: REMOTE 712 The 4300C should enter the remote state and illuminate the
REMOTE indicator. Verify that no other device on the bus was affected by execution of this command.
Reading the Display Data
The resistance data on the 4300C's display is always available to be read by the system controller. The
4300C does not require that a query or any other command be issued to retrieve it. Also, the 4300C does
not need to be in REMOTE for the display to be read. Retrieving the data will clear the reading buffer. The
controller must then wait until the next update of the A-to-D converter before a new value becomes
available. Data may be read at the rate of 2½ readings per second for a 4300C.
The fact that the readings are always available simplifies measurement retrieval. Every time the system
controller polls the 4300C's address, an instantaneous resistance value is returned corresponding to the
displayed value.
The following program shows an example of retrieving a resistance measurement from the 4300C. The
program is written in HP Basic. If you are using a programming language or package other than HP Basic,
consult your Programmer's Manual for the correct command syntax. The 4300C is assumed to be at
address 12.
10
ENTER
712;
A$
20
A$
30
GOTO
10
40
END
The execution of this program results in a continuous display of the resistance measurement, updated at
the conversion rate of the instrument's A-to-D converter.
Summary of Contents for 4300C
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