User manual

2400 Series SourceMeter
®
User’s Manual Remote Operations 14-15
Flow control (signal handshaking)
Signal handshaking between the controller and the instrument lets the two
devices communicate with each other about readiness to receive data. The
SourceMeter does not support hardware handshaking (flow control).
Software flow control is in the form of XON and XOFF characters and is enabled
when XON-XOFF is selected from the RS-232 FLOW CONTROL menu. When
the input queue of the unit becomes more than I full, the instrument issues an
XOFF command. The control program should respond to this and stop sending
characters until the SourceMeter issues the XON, which it will do once its input
buffer has dropped below half-full. The SourceMeter recognizes XON and XOFF
sent from the controller. An XOFF will cause the instrument to stop outputting
characters until it sees an XON. Incoming commands are processed after the
<CR> character is received from the controller.
If NONE is the selected flow control, there will be no signal handshaking between
the controller and the SourceMeter. Data will be lost if transmitted before the
receiving device is ready.
RS-232 connections
The RS-232 serial port is connected to the serial port of a computer using a
straight-through RS-232 cable terminated with DB-9 connectors. Do not use a null
modem cable. The serial port uses the transmit (TXD), receive (RXD), and signal
ground (GND) lines of the RS-232 standard. Figure 14-1 shows the rear panel
connector for the RS-232 interface, and Table 14-2 shows the pinout for the con-
nector.
If your computer uses a DB-25 connector for the RS-232 interface, you will need a
cable or adapter with a DB-25 connector on one end and a DB-9 connector on the
other, wired straight through (not null modem).
Figure 14-1
RS-232 interface connector
9876
54321
Rear Panel Connector
RS232