2 - Introduction to Programming
RS-232 Capabilities of the Electronic Load
The electronic load provides an RS-232 programming interface, which is activated by commands located
under the front panel Address key. All SCPI commands are available through RS-232 programming.
When the RS-232 interface is selected, the GPIB interface is disabled.
The EIA RS-232 Standard defines the interconnections between Data Terminal Equipment (DTE) and
Data Communications Equipment (DCE). The electronic load is designed to be a DTE. It can be
connected to another DTE such as a PC COM port through a null modem cable.
The RS-232 settings in your program must match the settings specified in the front panel
NOTE:
Address menu. Press the front panel Address key if you need to change the settings.
RS-232 Data Format
The RS-232 data is a 10-bit word with one start bit and one stop bit. The number of start and stop bits is
not programmable. However, the following parity options are selectable using the front panel Address
key:
Seven data bits with even parity
EVEN
Seven data bits with odd parity
ODD
Seven data bits with mark parity (parity is always true)
MARK
Seven data bits with space parity (parity is always false)
SPACE
Eight data bits without parity
NONE
Parity options are stored in non-volatile memory.
Baud Rate
The front panel Address key lets you select one of the following baud rates, which is stored in non-volatile
memory:
300
600
1200
RS-232 Flow Control
The RS-232 interface supports the following flow control options that are selected using the front panel
Address key. For each case, the electronic load will send a maximum of five characters after holdoff is
asserted by the controller. The electronic load is capable of receiving as many as fifteen additional
characters after it asserts holdoff.
The electronic load asserts its Request to Send (RTS) line to signal hold-off
RTS-CTS
when its input buffer is almost full, and it interprets its Clear to Send (CTS)
line as a hold-off signal from the controller.
There is no flow control.
NONE
Flow control options are stored in non-volatile memory.
16
2400
4800
9600
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