Follow these steps to get the BACnet client started up.

1. Connect your PC to the Babel Buster 485XL BACnet port (NET terminals next to power) via an RS-485 interface. This may consist of an adapter on a standard PC COM port, or a USB to RS-485 "dongle" with its manufacturer's drivers installed to make it appear as a COM port.

2. Initialize the stack. Select the COM port that your RS-485 interface is connected to or configured as. Select the baud rate. The Max Master count will default to 3 unless you enter some other number. For configuration use, it is suggested that you keep this number low. Click Init Stack. Once clicked, the BACnet MS/TP protocol stack will begin polling. You will need to close the program and restart to change baud rate or com port once the stack has started.

NOTE: If you are uncertain of the station ID, device instance, or baud rate your Babel Buster 485XL is currently set to, hold the INIT button down for about 30 seconds (until you see red LED inside) after you power it up. (Wait for initial power-up red LED to go out, then hold INIT button until you see red LED again.) This will force it to reset with temporary defaults of station ID=1, device instance=1, and baud rate=9600. Out of the box as shipped, it will default to station ID=1, device instance=2, and baud rate=9600.

3. Look for your device. Until the stack finds your device, you cannot communicate with it. Enter the device instance your gateway is currently configured for (see note above), and click Find. This sends out the "Who Is" message.

You need to click Find once to send the initial Who Is, and click it a second time to see if you got a response. If you are lucky, you will get "Found device" right away, but you may need to click Find a few times. If it still does not find your device after a number of tries, close the program and restart the stack. MS/TP is picky about character timing, but Windows is rather sloppy about it, so the Windows comm's driver often gets unhappy.

Make sure you are looking for target device 2 unless you reconfigured it otherwise, or unless you performed the INIT sequence.

4. Test the connection. Once MS/TP finds your device, you can test the connection by simply clicking Read. You will be reading Analog Input object #1 if you have not clicked anything else on the screen yet. You do not need to have any LonWorks network variables mapped to read a BACnet object. It will just return a value of zero. The example below illustrates reading an object from a previously configured gateway. This area of the screen is for diagnostics only, does not configure anything, and should always respond with a value when an object is read.

5. Proceed with configuration as applicable. You will now begin to use all other areas of the screen. Refer to the overall configuration tool help, and click on each area of the dialog box screen shot to review instructions for that area.

About ReSync: Once you click the Init Stack button the first time to start up the MS/TP stack on your PC, this button changes to ReSync. If you begin to have communication problems, especially after initially succeeding, simply click the ReSync button. Often this will recover the MS/TP stack on your PC. Since the PC is not proficient at character I/O with tight timing constraints (as required by MS/TP) the PC easily gets out of sync.