How does HART handle multiple masters on the same loop?

How does HART handle multiple masters on the same loop?

• A. Multiple masters are standard and can arbitrate automatically
• B. A single primary master is used; multi-master is not standard
• C. There are no masters; devices poll themselves
• D. Masters must be synchronized with a central clock

Answer: (B)

HART operates in a master-slave fashion with a single primary master controlling the loop. All digital communication is initiated by that master, and devices respond when asked. There isn’t a standard mechanism for multiple masters to contend or arbitrate access on the same loop, so multi-master operation isn’t part of the standard. You can connect secondary handheld communicators or similar tools to diagnose or configure devices, but they do not become active masters that can run concurrently with the primary master. If two masters tried to talk at once, the digital signals would collide, which is why the system relies on one primary master to schedule exchanges. That’s why the correct assumption is that a single primary master is used and multi-master isn’t standard. The other options don’t fit because HART relies on one master driving the communication, not devices polling themselves or requiring a central clock, and there isn’t automatic multi-master arbitration defined.

HART operates in a master-slave fashion with a single primary master controlling the loop. All digital communication is initiated by that master, and devices respond when asked. There isn’t a standard mechanism for multiple masters to contend or arbitrate access on the same loop, so multi-master operation isn’t part of the standard. You can connect secondary handheld communicators or similar tools to diagnose or configure devices, but they do not become active masters that can run concurrently with the primary master. If two masters tried to talk at once, the digital signals would collide, which is why the system relies on one primary master to schedule exchanges. That’s why the correct assumption is that a single primary master is used and multi-master isn’t standard. The other options don’t fit because HART relies on one master driving the communication, not devices polling themselves or requiring a central clock, and there isn’t automatic multi-master arbitration defined.