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Cooperation with the HART Communications Foundation continues in order to find a better way integrate ISA100 with WirelessHART. The technical problem is that the protocols used by ISA100 at the layers above the PHY/MAC must be robust enough to be used for many industrial applications intended for ISA100, whereas WirelessHART needs only to provide relatively limited HART data.
Several suppliers have already indicated their intentions to build adapters to interface wired HART field devices with ISA100 networks (referred to as “HART over wireless.”) Most of them have also indicated their intent to build WirelessHART devices and adapters for wired HART transmitters and valve positioners. The users working on the ISA100 standard are pressing for a less confusing situation than to install and configure two different networks in their plants.
The schedule for the ISA100 standard remains as previously announced:
|Principles of Operation draft||Q2, 2007|
|Principles of Operation release||Q3, 2007|
|Preliminary draft ISA100 Standard||Q4, 2007|
|Draft ISA100 Standard letter ballot||Q4, 2007|
|ISA100 Standard release||Q1, 2008|
|Test Plan||Q4, 2007|
|Test Procedure||Q1, 2008|
To interpret this schedule: the Principles of Operation describes how each part of the standard will accomplish its work. The standard adds actual protocol specifications to the Principles of Operation. The letter ballot is the formal voting process used by ISA and all standards committees. This ballot will be conducted by ISA simultaneously with the ANSI (American National Standards Institute) Public Comment and Review process. This means that a very broad audience will be able to examine the draft standard in order to provide comments, catch errors and recommend changes. The standards voting process requires all negative ballots to be accompanied by appropriate technical comments. Editorial comments with changes are also accepted, but are not sufficient to reject the standard. The committee must process every comment and make the suggested changes, if appropriate, and request any negative votes to be changed to positive if those changes are made. It is only reasonable that technical comments submitted without a suggested change in the standard will be rejected. The committee may also reject any comment with reasons for the rejection communicated back the source of the comment. [Author’s note: WirelessHART is a private specification that does not need this formality for approval by its membership, but this lack of public review precludes it from being a formal standard.]
Meanwhile, the ISA Standards Compliance Institute has created an entity called the Wireless Compliance Institute (WCI) for the purposes of administering the conformance testing of ISA100. This organization will be responsible for preparing the scheduled items called the “Test Plan” and the “Test Procedure” shown in the schedule. ISA has already begun the formation of the WCI, which is expected to be an independent non-profit, membership-driven organization that will assume ownership of the ISA100 standard and be responsible for the conformance testing of devices expected to bear the compliance logo, similar to the logo shown. This organization is expected to be somewhat similar to the Fieldbus Foundation in its responsibilities and governorship. It will be self-sustaining through membership dues and testing fees. The ISA is currently accepting initial donations to help fund this organization and to secure a seat on the initial board of directors.