DIgi-Star Scoreboard read

Projects Networking, Protocols, and Devices
1

Rather simple project in definition, but over my head in coding.
I am trying to trigger three digital outputs based on a switch (simple enough) and a scale reading on one of our mixer trucks. When the scale reads 3000 i want one output to come on for an engine set speed. when it reaches 10,000 i want the other output to go high to trigger a different engine speed. The truck interface is digital inputs, so rather straight forward. However I can't figure out how to read the serial data from our scales. I got help from digistar to get my scale set to the proper 9600 baud and output.

Here is the information in the tech manual from Digi-Star. Any help would be appreciated.
5. RS-232 Specifications

5.1 Signal Levels

The Printer, Computer, and Scoreboard are capable of communicating using the EIA
Registered Standard #232 (RS-232). The signal levels move between +8 and -8 Volts.
The Scoreboard also has another communication port that drives 20 milli-Amp devices.

5.2 Communication Parameters
Data is transmitted and received in the asynchronous ASCII format. This communication
format is compatible with most printers, computers, and terminals. The Alternate Port
Configuration is used when the Scoreboard Mode (SCOREM) is set to 4.

Standard Port Configuration
1200 BAUD
1 Start Bit
7 Data Bits
1 EVEN Parity Bit
1 Stop Bit

Alternate Port Configuration
9600 BAUD
1 Start Bit
7 Data Bits
1 EVEN Parity Bit
1 Stop Bit

“Handshake lines” are not used and XON/XOFF is not supported.
These parameters are not adjustable in the scale. Equipment interfacing to the scale
must match this configuration.

2

As you didn't specify your Arduino model you must use an UNO. There you have to use the hardware serial interface (the same as you might have used for debugging!) as only that one supports 7bit and a parity bit.

Serial.begin(9600, SERIAL_71E);

That should enable your Arduino to read the scale values once you get the hardware correctly connected. As your scale has a RS232 interface you must use a corresponding driver at the Arduino side. A MAX232 should do that job. Never connect the RS232 signals directly to the Arduino, most probably it would immediately fry it.

3

Thank you. It is an Uno...and yes i went direct to the board with the output. Golly i hope i didn't fry this.