smoothing and combining analog signals in Logo!8

Hi,

i would like to know if it is possible with a Logo!8 and an analog output module (and if so, how) to take two 0-10v analog inputs, take the average value of one of these inputs over the course of a minute say, then combine this average value with the other input value to give an analog output which is an average of these two values. the input value which is averaged over a minute should update every minute (or whatever time I decide). i would appreciate any help.

It may help if I explain the application (perhaps someone has a better solution).

I want to control the level of dough in a continuously filling and emptying hopper at a specific level (and be able to change this level for different dough). I have a laser height sensor with a 0-10v output monitoring the dough height and a 0-10v signal from a digital potentiometer to set the control level. I want to combine these two signals to send a 0-10v or 4-20ma signal to an inverter which controls the rate the dough is fed into the hopper. I could have just connected both signals to the inverter and used a parameter to combine them for speed control, but the problem is, the dough falls into the hopper in random sized chunks so the level is not flat like a liquid and this causes the laser level sensor output to constantly fluctuate as bigger or smaller pieces drop under it's beam and this makes the motor speed fluctuate too much. there is no smoothing built into the sensor, and no adjustment of inverter parameters has made a significant distance. I don't need a rapid response because the hopper level changes very slowly as it is constantly emptying and filling and so roughly balances out. so updating the signal from the sensor once a minute or so should be fine.