I've been using this app for sometime now and it is great, does what it says on the tin.
Works fine for one device, but more that one usb2serial device and the device selection in the preferences can only find the device manager software, rather than the subdevices, eg. /dev/tty.usbserial, /dev/tty.usbserial2.
So unfortunately i can't use it anymore. :(
Is this still being developed?
Silica
heads-up caller ID display utility
Version: 1.2