Flowserve MX FOUNDATION Fieldbus Field Unit - Manual (Page 8)

MX/QX FOUNdaTION Fieldbus Field Unit FCd LMENIM2330-01 – 08/11
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1.5.1 General Network Specification
System Specifications:
• Communicates using the FOUNDATION fieldbus protocol
• Employs high-speed communication
• Complies with the IEC61158 fieldbus standard.
Network Specification
Several topologies are available, point-to-point, bus with spurs, daisy chain, tree, or a combination of
these. Network features include:
• Link Active Scheduler controls the system
• High-speed communications up to 31.25 kbits/s
• Peer-to Peer communication.
MX/QX FF Field Unit Specification
The field unit mounts in the actuator and is software controlled in order to allow functionality of:
• Input and Output Function Blocks
• Proportional Integral Derivative (PID) Function Block
• Device descriptions
• Network communication
• Parameter configuration by user.
Link Active Scheduler Specification
Fieldbus segments have one, and only one, active Link Active Scheduler (LAS) at a given time. The
LAS acts as the bus arbiter, and does the following:
• Recognizes and adds new devices to the link
• Removes non-responsive devices from the link
• Schedules control activity in, and communication activity between, devices
• Regularly polls devices for process data
• Distributes a priority-driven token to devices for unscheduled transmissions.
System Host Specification
The system host is usually a distributed control system (DCS), or some other intelligent device. The
host does the following:
• Acts as the system LAS
• Issues requests for process data from the field devices
• Issues commands to the field devices
• Interfaces with any process control going on between network devices.