I've connected pin 4 (RX) to my Arduino UNO pin 1 (tx) and pumpI don't think you will get very far with this approach for a few reasons. Here's why.
an ascii letter 'A' to it and cycle thru baud rates from 1200 to 38400... but the cursor never moves nor
does the letter 'A' appear.
The SP232ECT converts RS232 signals to TTL signals. This means that the RX and TX lines are expecting RS232 level signals, +3 to +15V for a logical '0' and -3V to -15V for a logical '1'.
The KS0066F is the actual LCD Controller which contains all of the memory and also drives the 16 characters on the left hand side of your display. The HD44100H is an Auxiliary Controller which is used to drive the 16 characters on the right hand side of your display.
The LCD controller chip is expecting 2 or 3 control signals and 4 or 8 data signals at it's input which leaves the K0V498 as the interface between the serial signals from the RS232 transceiver and parallel signals that the LCD controller is expecting. Most likely it is some sort of microcontroller with all those pins. The red DIP switch could be setting the baud rate that this device is expecting.
This causes a underbar cursor to be displayed in pos 0 (row 1, col 1). This part is good news. It means that your LCD is powered and is being properly initialized.
You will have to come up with some way to generate true RS232 voltage levels to send to this device. If you have an ancient computer with a serial port, or a USB to RS232 adapter for a newer computer, you could use a terminal program such as Hyperterminal and tinker with various baud rates and protocols.