Monday, August 29, 2011

Introduction to Serial Sender

Serial Sender is Seetron's free utility for sending data bytes and strings of text through the serial port of a Windows PC ('95 through Windows 7). It's small (64kB) and simple, requiring no installation. Serial Sender won't replace a terminal program for bidirectional communication, but it's excellent for testing and demonstration of serial displays. This article presents a few screenshots showing how it works.

Radio buttons set the serial data rate (1200-9600bps) and select the comm port number (1-8).That's the extent of the configuration. The program does not mess with the port until you actually press Send, so it generally plays well with other port-aware programs.

To send text out the port, type your message and click Send. To send individual bytes, enclose the decimal value of the byte inside less-than < and greater-than > brackets. For example, the screen below sends a single byte (12 decimal, 0x0C hex, 00001100 binary) followed by the text "Hello World!" (The byte 12 is the clear-screen instruction for most Seetron displays other than BPI- and BPK-.)

The next shot sends the same byte and text, but uses the control-code symbol (ctrl-L) to express ASCII 12. Our docs refer to the control codes by letter and number, so you can use whichever is clearer or easier to remember.

Multiple bytes can be sent in a single set of brackets by separating them with commas. (This example clears the screen with ctrl-L and turns on the backlight with ctrl-N.)

The next example mixes control-code notation with numeric; ctrl-P is the position instruction, the number following is the screen location. Screen locations are expressed by adding 64 to the actual value, so 89 in the example is location 25 on the screen. (The offset of 64 has to do with the way that ASCII character codes are organized; don't worry about it.)

To save the aggravation of adding 64 to express values like screen location, Serial Sender can do it for you--just tack an underscore in front of the number. The last screenshot works the same as the previous one.

In a future blog, we'll cover some more Serial Sender hints and tips.

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