magnetic sensor and counter circuit issue

[howie]

water gate position gauge

Hello guys,

I am designing a data logger specifically for flood control stations so I have to pattern my design into the parameters needed by the site. One of its requirement is that I need to remotely control (using LAN) a Water Gate panel into its desired positions.

The system consists of a gate motor, with its shaft connected into a mechanical gauge through a chain. The guage determines every position of the water gate level. There are four positions indicated on the guage (labelled 1, 2, 3 & 4) so once the motor shaft turns the needle of the gauge increases and should be manually turned off once it reaches the desired position. I previously thought of using a magnetic sensor and frequency to voltage converter to measure the rate of speed of the motor shaft. But since the rate of speed of the motor remains the same, the voltage output will also be the same in all gate positions.

I am planning to use a counter to measure the number of turns the shaft would accumulate on every position so I can determine the number of turns on each position (1 to 4).

Can someone help me on a device or an idea on how to do this circuit? Or do you have any other idea regarding this matter?

Thanks.

 

[kender]

magnetic sensor, counter

Since you have a LAN interface, there's probably a microcontroller (uC) in your system. Some uCs (e.g. PICs) have counter peripherals in them. You can also connect the output of your sensor to an interrupt input on the uC and increment the counter variable in the ISR. Hope that helps.

BTW 1. I think, counting the shaft turns is a convenient way of monitoring the position of the gate. However, monitoring the position (linear? angular?) of the gate itself would be more reliable. That way, for example, you can detect fault modes where motor is turning, but the gate isn't moving (e.g. chain or gears broke).

BTW 2. Here's another good place to discuss sensor subjects: **broken link removed**

- Nick