The serial port drives and powers an LCD module of 16X2 characters. Included a VB6 software, PIC C code and
a circuit diagram. The VB application transmit only the last input byte to avoid overflow of the receive register of the PIC16F628A.
The serial port can source about 4 mA which is enough to drive the pic and the LCD module. The serial port can't power LCD with LED back light.
You can read more about serial interface in http://www.beyondlogic.org/spp/serial.htm
VB6 code, PIC code and circuit diagram download (20KB). You are free to use the circuit diagram and the VB software with no limitations.
See also Technical Tips
Pin 4 at the serial port is
turned to +12V by the software enabling RTS. It is regulated to
5V by 78L05. The 5V is the supply to the microcontroller.
Pin 3 is used to drive RX input, BC337 reverse the signal phase.
LCD display and driver has 14 way connector, 10 connections are used, 4 bits data bus is selected. There is a big selection of LCD modules, and they are very similar in characteristics i.e. DM1601, ACM1601.
Vss - Supply GRD.
Vdd - Supply 5V
Vo - Contrast Adjust
RS - Register Select
R/W - Data Read/Write
E - Enable
D4-D7 - Data Bus Lines
LCD module is 20K pot is the LCD contrast, make sure it is set.