Project Delivery

On the Go With HMI - Approach to Handheld HMI's in the Workplace

As Appeared in the 'Real Answers' Column - Control Design - April 2012

April 12, 2012

Following is Interstates' response to a Control Design reader's question. "We integrate multiple machines into a complete manufacturing process line. The operator has to physically attend to all of the machines. Rather than have an HMI at each machine, we're thinking about handheld HMI, maybe wireless, that the operators would carry with them. We'd like to hear about experences with this approach."

Single-Operator Capabilities The ease and cost of deploying your handheld HMI solution will depend on a couple of criteria: the level of functionality you desire from the handheld, and your current infrastructure.

A remote access capability that allows operators and plant managers to view the system from anywhere can be quite simple. Being able to see the entire operation in real time can be extremely helpful when a plant manager or maintenance personnel get a call from an operator in the middle of the night, allowing them to log in remotely to either dismiss the alarm or help the onsite team troubleshoot over the phone. If you are looking for the full functionality of your current stationary HMI in a mobile platform, a system integrator or your distributor can help you determine the best design and components to use

We recently installed a mobile HMI that offered full manual control of all machines and devices at a flour mill. The mobile HMIs also have barcode scanners, so operators can scan a machine or component and the HMI automatically will bring up the manual control screen for that device.

Prior to getting the handhelds, in the case of an alarm, a plant operator would have to travel as many as six stories to the control room to acknowledge the alarm and identify the issue before heading out to the device to enact necessary changes, only to then return to the control room to reset the alarm. Mobile HMIs allow operators to see an alarm from any area of the plant and immediately log in to the manual control screen to reset the alarm (if all is well), or make the necessary changes to fix the problem and restart all from their mobile location. This also allows the facility to run with only a single operator on staff at any given time.

We selected Intermec model CN4-C PDAs as the mobile HMI hardware for this facility primarily because of the intrinsic safety rating. The plant had an existing control system that used FactoryTalk View Site Edition HMI software from Rockwell Automation for visualization. We created an app for FactoryTalk View SE that allows the PDAs access to the system via remote desktop session. The screens from the stationary control system HMI were optimized for the mobile platform.

A centralized security service adds the ability to configure user and group permissions within the system so only verified users are able to log in via the stationary system or the mobile HMIs. If you require additional levels of security, certain vendors offer secure overlays for handheld devices.

If you are working from your existing control system and have a visualization application already running that you can tap into remotely, you will save the cost of purchasing that server, as well as a new software licensing fee. A wireless infrastructure would be required, and you would want to confirm you do not have problematic weak signal points in your facility. Additionally, you will need to determine what devices would work best in your plant environment. Many of our customers are excited about the capabilities of the latest consumer devices, only to determine they need a device that can hold up in an industrial setting. This could involve anything from the temperature rating of the hardware to requiring the ability to clip on to the body for use on a manlift or other plant equipment, for example.

A mobile HMI solution can save a lot of time and money, but the investment in creating the solution could vary greatly depending on what functionality you desire from the mobile platform, your current wireless infrastructure, and what control system you already have in place.