Interface Operation
The Agilent 1670G-series logic analyzer can be programmed with a controller
over RS-232-C 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 Agilent 1670G-series over RS-232-C 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 a 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-232-C link. For both three-
wire and extended hardwire operation, the DCD and DSR inputs to the logic
analyzer must remain high for proper operation.
With extended hardwire operation, a high on the CTS input allows the logic
analyzer to send data, and a low disables the logic analyzer data transmission.
Likewise, a high on the RTS line allows the controller to send data, and a low
signals a request for the controller to disable data transmission. Because
three-wire operation has no control over the CTS input, internal pull-up
resistors in the logic analyzer assure that this line remains high for proper
three-wire operation.
RS-232-C Cables
Selecting a cable for the RS-232-C interface depends on your specific
application, and, whether you wish to use software or hardware handshake
protocol. The following paragraphs describe which lines of the
Agilent 1670G-series logic analyzer are used to control the handshake
operation of the RS-232-C bus relative to the system. To locate the proper
cable for your application, refer to the reference manual for your computer or
controller. Your computer or controller manual should describe the exact
handshake protocol your controller can use to operate over the RS-232-C
bus. Also in this chapter you will find cable recommendations for hardware
handshake.
Programming Over RS-232-C
Interface Operation
3–3