LAMBDA DG-4 PLUS & DG-5 PLUS OPERATION MANUAL – REV. 3.05B (20131009)
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Figure 4-3. Serial control connections (viewed from rear of cabinet).
Communication for the serial port requires the following settings:
Data Rate:
9600 bps (bits per second) or “baud”
Data Bits:
8
Parity: None
Stop Bits:
1
Flow Control:
None
No hardware control lines are connected. The communication mode must be set so that
either these lines are ignored, or connections to these lines are made that satisfy the
communications mode desired. In Microsoft Quick Basic, the communication channel may be
opened with a statement such as:
OPEN “COM1:9600,N,8,1, CD0,CS0,DS0 “ FOR RANDOM AS #1 LEN = 256
This sets COM1 to the correct mode for bi-directional communication through channel #1.
The option list “CD0,CS0,DS0” causes Basic to ignore the DCD, CTS and DSR control lines.
In order to send commands to the Lambda DG-4 via the serial port, you must first place the
Lambda DG-4 in the serial mode. If the Lambda DG-4 is in either the parallel or manual
mode it can be placed in the serial mode by simply sending the decimal value 238 (EE
hexadecimal) via the serial port. Do not send this data value by both the serial and parallel
port, since this will cause the controller to rapidly switch between modes. If you send 238 via
the serial port, it will be retained as the serial input until another serial command is received.
Thus, if you send it via the serial port and do not send another character, neither the manual
nor parallel modes can be selected for proper operation.
The mode is indicated on the front panel display. The display will indicate either PARALLEL,
MANUAL OR SERIAL. The unit automatically selects the parallel mode at power on. When
the value of 238 is received, the display will switch to indicate SERIAL. If any communication
errors occur, they will be indicated by the * symbol following the word SERIAL. If the 238
command is not received correctly because of communication errors, the * symbol may
replace letters in the word PARALLEL.
4.2.2
Controlling the Lambda DG-4 from a Computer’s Serial Port
Each 8-bit command listed under the parallel port instructions can also be sent through the
serial port. Since the serial data format used is 8 bit, each character sent is a command. If