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Getting Started

WirelessHART technology brings a new dimension to the world of process automation. Building on the proven success of the HART Protocol, the WirelessHART extends the reach of process instrumentation in a way that is compatible with existing systems and practices.

Let’s review the straight-forward steps needed to ensure a successful WirelessHART installation.

Planning a WirelessHART Project

  1. Scope the Project
    1. What are the objectives for the project – PV monitoring, non-critical control or Instrument condition monitoring. The answer to this question will affect the devices you select - battery powered instruments or WirelessHART adaptors for example.  As part of the scope, be sure to review; area of network coverage, density of the area and primary and secondary instrumentation.
  1. Planning the Network
    1. There are several ways by which you can plan a network and allocate devices. They are similar to those used when allocating instruments to I/O cards in a PLC/Controller, however, there are some new considerations such as gateway placement and update rates.
    2. WirelessHART could have little impact here, however there will be some things that are new. For example, the instrument data sheet and I/O schedule will need to reflect new information such as Network-ID – Join Key – Refresh Rate.
  1. Host Integration
    1. Here the emphasis is upon using existing protocols (Modbus – Profibus) for host integration and existing tools for instrument configuration. The new consideration is security – which is built-in!

Device Placement

Don’t forget this is a mesh network. Instruments do not need to be within the range of the gateway but rather just need to be close to another wireless instrument.

Tips for Network Planning:

Device Specification

WirelessHART devices are all basically the same when it comes to their wireless characteristics. The device should be registered with the Foundation which is an indicator of a good wireless design and interoperability with other suppliers’ products.

Verify the range of the antenna since some devices may offer antenna options that will alter the distance assumptions.

Factory Configuration - Decide if you want the network ID and join key entered by your supplier (if offered)

Commissioning and Checkout

Planning a WirelessHART network is a fairly simple process. Common sense rules provide the guidance for a successful installation.  Here are a few things to remember:

A HART handheld or PC tool will allow you to join instruments to the network.  Overlapping networks will have different network ID’s.

  1. Steps – the Gateway
    1. Install and power Gateway
    2. Install devices one by one
      • Begin with closest to the gateway

  2. Steps – the WirelessHART Device
    1. Install or activate the device’s power source
    2. Enter the Network ID
    3. Enter the Network Join Key
    4. Set the refresh (update) rate
    5. Verify the device has joined the network
      • At the device using a handheld or other tool
      • At the gateway
  1. Steps – Commissioning a WirelessHART device
      • Verify Device Operation
        1. Check device TAG
        2. Check device engineering units
        3. Check PV Update rate
        4. Check battery voltage
      • Verify Gateway
        1. Check for minimum of 5 direct connections
        2. Check for 25% of devices with direct connections in large networks with <10% add repeaters if necessary

Commissioning a WirelessHART network

After all devices have been commissioned, allow time for the network to optimize (>4 hours).  Check each device for at least 3 neighbors and check path stability for 60% minimum.  Increasing the elevation of the antenna can correct many situations and add a repeater if necessary.

Security

Allowing Access to the Network through Key Management including Network ID Key Management includes a global key for all devices, individual key for each device, Join Key – Fixed, Rotating or Assignment at the factory with order or on the bench.  White Lists may include only “approved” devices allowed or requires an approval procedure

Best Practices