HMI, PLC & VFD's communication

I have one 15Hp Delta VFD c-2000 series, two 3 Hp Delta E series VFD's , DElta DOP-B HMI & Delta DVP 14ss2 PLC. I want to control the weight of the our product through weighing machine connected to plc with compatible Load cell module.With this I have to run all the three motors in closed loop to automatically vary the speed of the three motors for controlling the weight of the product. The three motors will run with different ratios. The ratios of the three motors may change with different items, we are manufacturing. I want to know what things will I be needed apart from the Load cell module. I mean if I need analog output module. currently I am varying frequency manually by potentiometer. Also I want to know about modbus communication & which Load cell module , I will be needed.
Can anyone help.
Regards,
Subhash B. Talreja
Contact No. 9890191949

Delta do a load cell module so i would use that first. Then use modbus to link to each drive.
Much easier and less wiring and easier to programme.

Cheers,

Brett