OH 1.8.3 users (like me) should note that they can take advantage of later Modbus binding 1.10
Version 1.9 offered real improvements with serial connections, 1.10 builds on that and also includes new functionality.
It may not matter much if your only Modbus device is the Nilan, but if you happen to have other Modbus RTU or TCP devices as well I would recommend binding update.