Details
Question
Can a DataMan receive data from over RS232 and include that data with the read results going back to a PLC? For example - A DataMan is connected to a scale which sends data over RS232 - reads weight - weight goes to the DataMan and gets included with the read results being sent to the PLC.
Answer
There are several methods to accomplish this. The following is a simple method that can be altered to suit your needs. The method involves using two scripts - one Data Formatting script, and the other a Communications script.
BACKGROUND INFORMATION - serial devices are often configured to send, along with its data, a header and footer. These serial devices (not all) often use these specific ASCII control characters for start of text - STX (ASCII code 02) and end of text - ETX (ASCII code 03). This is the serial device's way of saying - my data is starting here and ending here. If that were the case we write the line below:
this.expectedFramed("\x02", "\x03",128);
Review the serial device's documentation to determine what header and footer is being used - some allow configuring the device with a unique header and footer.
A scale measuring weight (for example) reading 15.253oz sends the following:
\x0215.253oz\x03
The communications script will get the data from the device in the format above and store the data between the header and footer as a variable - Swag.
Now the camera is ready to take it's read results and include the Swag. We have included a space between the serial number and weight for clarity:
output.content = decodeResults[0].content + " " + Swag;
The following could be sent to the PLC:
8675309 15.253oz
In regards to the communications script - the two key points are the onConnect "this.expectedFramed("x", "z", n);" where x is the header, z is the footer, and n is the max number of characters. The other key point is the onExpectedData function. Here it will store a string that contains the data between the header and footer. In the following example I assigned it the variable name "Swag". This variable can then be referenced in the Data Formatting script:
function CommHandler() {
return {
onConnect: function(peerName) {
this.expectFramed("\x02", "\x03", 128);
return true;
},
onDisconnect: function() {},
onError: function(errorMsg) {},
onExpectedData: function(inputString) {
Swag = inputString;
return true;
},
onUnexpectedData: function(inputString) {
return true;
},
onTimer: function() {},
onEncoder: function() {}
};
}
Use the following for the Data Formatting script:
function onResult(decodeResults, readerProperties, output) {
if (decodeResults[0].decoded) {
output.content = decodeResults[0].content + " " + Swag; //If no data was received only content will be sent
Swag = "" //This will clear results for next trigger
}
}
