PURPOSE: To prevent transmitting unstable measuring data accompanied with the change of measuring sensitivity by transmitting information about the measuring sensitivity before the change in a fixed time when the change of the measuring sensitivity is detected with the aid of the sensor of a monitoring control device.

CONSTITUTION: When the measuring sensitivity range of a flowmeter is switched at (t1) o'clock, a change of state detection part 12 detects a change of state and outputs a change of state detection signal 12a. When the signal 12a is inputted to a timer part 17, the timer part 17 immediately begins timer operation, sends a set signal 17a and drives a transmitting data switching part 18. As the switching part 18 is set by the AND output of a scanning finish signal 19a from a transmitting control part 24 and a time-up signal 17b, a pair of switching means S1 is switched to the (b) side of a contact only in a fixed inhibit time β1. Therefore, data stored in a transmitting data memory part 21 before the change is transmitted only in the inhibit time β1 from (t1) o'clock.