function handle()
	local desired_rpm = GetCurSpindleRPM()
	if (not IsRealDeviceConnected()) then
		desired_rpm = 0
	end
	
	local value, is_online = ReadModbusRegisterUpdated("SpindleStatus")
	Sleep(30)
	local mode_updated = is_online and (value == get_mode(desired_rpm))
	
	if (prev_rpm == nil or prev_rpm ~= desired_rpm or not mode_updated) then
		if (send_spindle_control_command(desired_rpm)) then
			prev_rpm = desired_rpm
		end
	end
end

function send_spindle_control_command(rpm)
	local mode = get_mode(rpm)
	
	local Hz = math.floor(math.abs(rpm) / 60 * 10 + 0.5)
	
	local success_1 = WriteModbusRegister("SpindleMode", mode)
	Sleep(30)
	local success_2 = WriteModbusRegister("SpindleRPM", Hz)
	return success_1 and success_2
end

function get_mode(rpm)
	local mode = 3  -- Stop
	if (rpm > 0) then
		mode = 1  -- Forward
	elseif (rpm < 0) then
		mode = 2  -- Reverse
	end
	
	return mode
end