HP 1650B User Manual

Programming Over RS-232C 3
Introduction This section describes the interface functions and some general concepts
of the RS-232C. The RS-232C interface on this instrument is
Hewlett-Packard’s implementation of EL4 Recommended Standard
RS4!32C, “Interface Between Data Terminal Equipment and Data
Communications Equipment Employing Serial Binary Data Interchange.”
With this interface, data is sent one bit at a time and characters are not
synchronized with preceding or subsequent data characters. Each
character is sent as a complete entity without relationship to other events.
Interface
Operation
The HP 1650B/51B can be programmed with a controller over RS-232C
using either a minimum three-wire or extended hardwire interface. The
operation and exact connections for these interfaces are described in
more detail in the following sections. When you are programming an HP
1650B/51B over RS-232C with a controller, you are normally operating
directly between two DTE (Data Terminal Equipment) devices as
compared to operating between a DTE device and a DCE (Data
Communications Equipment) device. When operating directly between
two DTE devices, certain considerations must be taken into account. For
three-wire operation, XON/XOFF must be used to handle protocol
between the devices. For extended hardwire operation, protocol may be
handled either with XON/XOFF or by manipulating the CTS and RTS
lines of the RS-232C link. For both three-wire and extended hardwire
operation, the DCD and DSR inputs to the HP 1650B/51B must remain
high for proper operation. With extended hardwire operation, a high 0;
the CTS input allows the HP 1650B/51B to send data and a low on this
line disables the HP 1650B/51B data transmission. Likewise, a high on the
RTS line allows the controller to send data and a low on this line signals a
request for the controller to disable data transmission. Since three-wire
operation has no control over the CTS input, internal pull-up resistors in
the HP 1650B/51B assure that this line remains high for proper three-wire
operation.
HP 1650B/HP 16518 Programming Over RS-232C
3-l

HP 1650B Specifications

General

Brand	HP
Model	1650B
Category	Measuring Instruments
Language	English