This part of the screen serves three functions all related to communicating with the MS/TP port of the gateway. The first and most frequently used function is starting the MS/TP client protocol stack on the Windows PC. The second is reading and writing the MS/TP port parameters, and the third is causing a device reinitialization that results in the new MS/TP port parameters being saved and used upon device restart.
Windows MS/TP Client Startup
PC COM port: Select the port your MS/TP network is connected to.
Baud Rate: Select the baud rate your MS/TP network will run at.
Init Stack: Click to start the Windows client protocol stack. Once clicked, this button will be renamed ReSync. Clicking ReSync will force an effective restart of the MS/TP stack, without completely restarting the program, in the event the PC loses the connection.
Note: The value found in the Max Master window is used one time at stack startup by the configuration tool to set its own Max Master. After the stack is started, the Max Master parameter applies to the gateway's setting.
Device Connection
Target Device: Enter the device instance (device number) that the gateway is currently configured to be. If you hold the INIT button down long enough to restart the gateway (about 30 seconds), the device number will be 1. If the gateway is not in INIT mode, but has never been configured, it will default to device number 2.
Find: Click this button to send out a Who Is request to let the MS/TP stack identify the device. Refer to startup instructions for more about the Find button.
BACnet Device Settings
Device Instance: Each device on a BACnet network must have a unique device number. Enter the device number that should take effect upon reinitialization. This is up to a 22-bit number.
Baud Rate: Select the baud rate the gateway should operate at.
Station ID: Select the station ID for the local MS/TP segment of the network. This is an 8-bit number. Station IDs should start at 1 and count up. The configuration tool uses station ID 0.
Max Master: This value defaults to 3 in both the gateway and the configuration tool. Set it to a higher number if your station ID is higher than 3. You never need anything higher than 2 if you are configuring the gateway in its INIT mode. Otherwise the Max Master must be set at least as high as the station ID. However, it is a good idea to keep it low so that the configuration tool is not looking for a large number of masters - this will slow down response.
New Reinit Password: The reinit password can only be written in INIT mode. The default password is "buster". The password is required in order to issue a device reinitialization request.
Read: Click this button to read the present BACnet MS/TP port settings. The reinit password is not readable.
Write: Click this button to write the presently displayed parameters to the gateway, including the reinit password if in INIT mode.
Device Reinitialization
Old Reinit Password: You must enter the correct password before you can reinitialize the device from the network. The configuration tool issues a warm start request, which results in the MS/TP port parameters being stored to non-volatile memory, followed by a device reset (same as power-up reset).
Reinit Device: Click this button to send the warm start request.