I'm not able to replicate this issue with the BACnet IP devices I have on my test bench, but based on the error message I think you may need to install the fontconfig package. Log into the unit locally or via SSH (port 2222) and run the following command:
sudo apt-get install fontconfig
Hmm, then I would suggest setting it in the /etc/network/interfaces file. Download an SSH client like PuTTY and connect to:
Your unique SSH password would have been included on a sticker in the MangoGT box. If you need us to look it up, please send the serial number of the MangoGT to firstname.lastname@example.org. Use the following command to edit the file:
sudo nano /etc/network/interfaces
Then change this line:
iface eth0 inet dhcp
To be like this:
iface eth0 inet static
Ctrl+x, y, Enter to save. Then sudo reboot to restart the unit with the new static network settings. Gateway and DNS servers are optional if you don't need them.
Which device are you trying to change the network settings on? If it is a MangoGT, the module should work - you may just need to refresh without the cache (Ctrl+Shift+R for Chrome/Firefox). If you're trying to set a static IP for a MangoHTS, the MangoES Configuration module is not supported and you'll want to SSH into the unit and adjust the /etc/network/interfaces file.
Let me know if you need instructions for the latter.
Webmin was dropped going forward from the MangoES on both the MangoGT and MangoHTS, mainly for security considerations. While we haven't tested it on either, I don't see why following those instructions wouldn't work. The GT uses a Raspbian Lite OS, which is based on Debian.
Hey Matt - that frantically blinking Tx/Rx behavior you're describing is how the MangoES would act if it didn't have the eMMC drive fitted on the board. If you give it a gentle shake, can you hear anything rattling around in it? Those are usually secured to the board with a piece of mounting tape, but that may have been missed. If there's nothing loose in the case, it could be that the drive has become corrupted and is no longer booting.
Send a message into email@example.com with the serial number of the MangoES and I can check on the warranty status.
Just to chime in on your question - what are you using to measure the incoming line voltage? If it's an actual metering device or transducer, then the response time of that will probably be the bottleneck when it comes to the frequency at which you can get new, meaningful voltage values from it.
I don't know what the Click PLC might add on top of that, but I imagine Modbus TCP is going to be your best bet for quick polling (network traffic notwithstanding) versus the added overhead of BACnet/IP. All said, you're probably going to be looking at something around 100ms being your maximum reasonable polling rate. To get anything more granular than that, you'd probably need to consider a power quality meter specifically made to detect and log voltage events down at the cycle/sub-cycle level and those usually start at a couple thousand dollars, if memory serves.