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Computer Operation
6.1 Introduction
6.2 Capabilities
6.2.01 General
6.2.02 Operation
6.2.03 Communications Monitor Menu
6.2.04 Compound Commands
6.3 RS232 Operation
6.3.01 Introduction
The model 7124 includes RS232, USB and Ethernet interface ports, designed to
allow it to be completely controlled from a remote computer. Virtually all of the
instrument's controls may be operated, and all of the outputs can be read, via these
interfaces. In addition, there are a few functions, such as curve storage of the second
reference channel outputs in dual reference and dual harmonic modes, which can
only be accessed remotely.
This chapter describes the capabilities of the instrument when operated remotely and
discusses how this is done
All instrument controls, which can be set using the front-panel display menus, can
also be set remotely, with the exception of the Spectral Display controls, and the
User Settings. In addition, the present setting of each control can be determined by
the computer. All instrument outputs which can be displayed on the front panel, with
the exception of the Spectral Display, may also be read remotely.
Control of the lock-in amplifier from a computer consists of the computer sending
commands to the instrument, with it responding either by sending back some data or
by changing the setting of one of its controls. The commands and responses are
generally ASCII text strings, although transfer of data from the instrument's curve
buffer can also be done using a binary dump of values, with each value being two
bytes long.
The computer ports cannot be used simultaneously, but when a command has been
completed, the lock-in amplifier will accept the next command from any port, and
respond to that port.
A most useful feature of the model 7124 when troubleshooting communications
problems is the Communications Monitor menu, which is described in detail in
section 5.3.17. However, once the problem has been resolved it is recommended that
the instrument be reset to the Main Display mode to avoid slowing down
communications.
Unlike older SIGNAL RECOVERY instruments, the model 7124 does not support
compound commands, which are two or more simple commands separated by
semicolons (ASCII 59) and terminated by a single command terminator.
The RS232 interface is primarily intended to enable the lock-in amplifier to be
operated from a computer program specially written for an application, although it
can also be used in the direct, or terminal, mode. In this mode the user enters
6
Chapter
6-1
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