Wireless ethernet for mobile HMI


Thread Starter

Adam Goldberg

We are getting ready to modernize some of our older control systems with a more modern ethernet based (at least the HMI) control system. I want to add the capability for the operators/technicians to be able to wander around the entire plant with a mobile HMI and be able to be in touch with the control system using wireless ethernet. There are two parts to implement this - the wired access point and the mobile/client device

Access point - I have read plenty on various technologies. There are lots of different technologies available - as best I can tell, the industrial technologies generally use frequency hopping as the more reliable method of transmission, but at the penalty of bandwidth. I intend for the receiver/client device to be able to pull up the exact same graphics as a wired operator interface - reasonable bandwidth is of some concern. We are also outside with many cinder block and metal buildings, tanks, columns, structures, etc. The plant site is maybe 10 acres. Lots of vendors list ~30Km for line of sight distances with only several hundred feet for "inside" or I suppose not line of sight distances. Do I need lots of transmitters to effectively cover my area? What about the strength of the client's transmitter?

Obviously even if I have a strong transmitter for the access point, the client needs to be able to effectively transmit data back to the access point. I am not doing control with this wireless network - no PLC to PLC communication or anything like that - so it is not mission critical, but it is reasonably critical that the operator maintains communication with his process.

Along the lines of the mobile client, is there anything out there with reasonable resolution (at least 640 x 480). Anything rated for Cl I, Div II or Cl I, Div I? We would be using Windows Terminal Services at the server for the client to access the control system.

I would appreciate hearing about people's experience actually implementing a wireless network - especially outside with similar obstructions to ours.

Any information to help me figure out what to do would be helpful.

Look into RSView Studio and AB's handheld CE devices. RSView Studio will allow you to build HMI in Supervisory edition adn port same screens to either Panelview Plus or Tethered or Wireless new handhelds they make.

Haven't used but looks great in sales pitch...


DAVCO Automation
"The Developing Automation Value Company"
Check out Advantech's MPC-100 tablet PC. It's a lot of computer for the money. They also have wireless networking gear.


Adam Goldberg

The AB MobileView Tablet Terminal is kind of along the lines of what I am looking for. I would prefer two more features, however - a wireless HMI that is rated for at least Class I, Div II and one that uses frequency hopping instead of direct sequencing.

I am under the impression that frequency hopping has proven a more reliable ethernet transmission method than direct sequencing, at least with regards to an industrial setting - I would appreciate people's first hand experience on this matter.

We are using the compaq 3650 Ipac with a wireless 2.4 gig. Direct Secq. Network card, and using BreezeNet wireless access points. I am accessing (3) three Plc's on a 2000 windows terminial server machine using a program which we programmed in Visual Basic. The CE devices runs the Visual Basic program on the 2000 machine. We have anywhere from 1 to 10 Ipac's getting data and sending data back to any of these PLC's at any given time. This really works will and the Ipac has a great Screen