modbus stuff: 

flipper.py: flips modbus coil outputs from true to false and vice versa
over a range of bits. Operates on a grid, rows 0-4095, 16bits at a time 
for 0-65535.

Tested with mod-sim from plcsimulator.org

/flipper.py -h
Usage: flipper.py [options]

Options:
  -h, --help    show this help message and exit
  -s START      starting row
  -e END        starting row
  -i IPADDRESS  ipaddress to target

example: 
./flipper.py -s2 -e50 -i 172.16.8.2
flipping bits from 32,48
was [False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False]

Requires: 
pymodbus: https://github.com/bashwork/pymodbus
twisted: pip install twisted