http://itunes.apple.com/us/app/iplc-rw/id393751540?mt=8
Actually just updated to new version that solve little problems related to S7 connection (it was not working in my iPod before...). Now looks ok.
I just hope in new releases because it's quite poor actually...
Ever test it?
With iPLC RW you will able to establish IP communication via local Wireless Networks with PLC's via Modbus or Siemens TCP communication protocols.
Like SCADA applications, iPLC RW will allow you to create several links with different PLC's and for each link define points of different data types (bool,byte,word,integer,floating point) and read actual values.
Modbus:
Based on RFC791/RFC793 communication protocols, communicate with several types of devices that support Modbus request/reply protocol (TCP port 502). Based on
Siemens:
Based on RFC1006 communication protocol, communicate with Siemens S7 PLC series (TCP port 102). Simatic and STEP 7 are registered Siemens AG trademarks.