Hi Michele,
I am not an expect on the BACnet4J code, but I do try to dabble and help people a little when I can. But,
I think you cannot have an UnsignedInteger for a object with the type of AnalogInput. Looking in ObjectProperties suggests the following support a presentValue property set to the UnsignedInteger type:
ObjectType.
accumulator
command
multiStateInput
multiStateOutput
multiStateValue
positiveIntegerValue
So it sounds to me like you may be looking for,
systemStatus1 = new BACnetObject(localDevice, localDevice.getNextInstanceObjectIdentifier(ObjectType.positiveIntegerValue));
systemStatus1.setProperty(PropertyIdentifier.objectName, new CharacterString("System status group 1"));
systemStatus1.setProperty(PropertyIdentifier.units, EngineeringUnits.noUnits);
systemStatus1.setProperty(PropertyIdentifier.presentValue, new UnsignedInteger(65535));
localDevice.addObject(systemStatus1);