Remote operation 
  Copyright © Itech Electronic Co., Ltd.  78 
⚫  The electronic load asserts its Request to Send (RTS) line to signal hold-off 
when its input buffer is almost full, and it interprets its Clear to Send (CTS) 
line as a hold-off signal from the controller.   
⚫  When the input queue of the electronic load becomes more than 3/4full, the 
instrument  will  send  an  X-OFF  command.  The  control  program  should 
respond to this and stop sending characters until the electronic load issues 
the X-ON, which it will do once its input buffer has dropped below half-full. 
The electronic load recognizes X_ON and X_OFF sent from the controller. 
An X-OFF will cause the electronic load to stop outputting characters until it 
sees an X-ON.   
⚫  NONE there’s no flow control. 
Flow control options are stored in non-volatile memory.   
RS-232 connections   
The RS-232 serial port can be connected to the serial port of a controller (i.e., 
personal  computer)  using  a  straight  through  RS-232  cable  terminated  with 
DB-9 connectors. Do not use a null modem cable. The table below shows the 
pinout for the connector. 
If your computer uses a DB-25connector for the RS-232interface, 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).   
 
RS-232 troubleshooting: 
If you are having trouble communicating over the RS-232 interface, check the 
following:   
⚫  The  computer  and  the  electronic  load  must  be  configured for  the same 
baud rate, parity, number of data bits, and flow control options. Note that 
the electronic load is configured for 1 start bit and 1stop bit (these values 
are fixed). 
⚫  The correct interface cables or adapters must be used, as described under 
RS-232 connector. Note that even if the cable has the proper connectors 
for your system, the internal wiring may be incorrect.   
⚫  The interface cable must be connected to the correct serial port on your 
computer (COM1, COM2.etc.). 
Communication setting   
Before  communication  operation,  please  make  sure  that  the  following 
parameters of electronic load match that of PC. 
⚫  Baud rate  :9600(4800、9600、19200、38400、57600、115200). You can 
enter system menu through panel to set communication baud rate.