It reminds me of a situation I ran into w/ a Customer who wanted to monitor manufacturing process parameters from a production line. The line already had PLCs c

It reminds me of a situation I ran into w/ a Customer who wanted to monitor manufacturing process parameters from a production line. The line already had PLCs controlling the processes. Their PLC vendor advised them to just attach the PLC network to the rest of the LAN with a "firewall" to restrict access to "approved computers". I argued very strongly for independent PLCs connected only to sensors measuring the process parameters. There was no requirement to make modifications to the control PLCs from less-trusted networks anyway. I didn't win the battle, but I stand by my position and feel much the same way about cars.