Multiple Controller Drive

We manufacture precision metering equipments (metering pump + gearmotor). The gearmotor is connected to an inverter from which we vary speed using the built in potentiometer of the inverter.
We are designing a new metering system for a new customer, and he would like to have the possibility of varying the speed of the inverter remotely using a desktop or a laptop. The inverter accepts an external DC voltage supply of 0-10 VDC, 1mA.
1) Do you have a kit (hardware + software) to connect the computer to the inverter for speed varying?
2) Sometimes we manufacture multiple motors systems (8 or 10 motors), which rotate at different speeds because are used in different stages of a chemical process. Would it be possible to control all motors (or inverters) at the same time using one single kit and connection cable?. If, not, what is the maximum quantity of inverters that we could control?

If I understand correctly your motors are AC induction motors which you drive from a DC source via an inverter.
If I am wrong and they are DC motors or you can use DC motors (12 to 36 Volt) let us know as there could be other possibilities.
You can drive your inverter using a board that generates a DC voltage varying from 0 to 10 Volt DC according to an input from a laptop connected via RS232.
You may want to look at our AX500; the AX500 normally drives a load of several amps but it can drive a load to ground as well; if you use a simple resistor between output an ground the AX500 will generate a variable duty cycle square wave according to the input from the laptop. By filtering the square wave (16 kHz) with a capacitor you will obtain a DC. The filtering affect has to be light enough so the voltage will change in matter of tens of milliseconds to allow the motor to speed up or slow down.
The AX500 has its own response time to sudden variations accelerating and slowing down, plus the filtering affect so the best thing to do is to try and see if it does the job.
You can drive the AX500 with a laptop (see the instruction manual downloadable from www.roboteq.com) and one AX500 will drive two 0-10 Volt DC inputs so two motors. The AX500 comes with the appropriate software to drive the two motors.
Four AX500's can be driven just using a multiple RS232 converter; it is a "USB input/RS232 output" unit with 1 USB input and 4 RS232 ports; its cost is in the area of 70 dollars.
The software for four motors would have to be custom written, but it is fairly easy and we do provide source code in Visual Basic (downloadable from www.roboteq.com).