Flowserve MX FOUNDATION Fieldbus Field Unit - Manual (Page 27)

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MX/QX FOUNdaTION Fieldbus Field Unit FCd LMENIM2330-01 – 08/11
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3
Software
3.1 Fieldbus Protocol
The fieldbus system uses the FOUNDATION fieldbus protocol to communicate over the H1 Fieldbus
network with other Fieldbus devices. The signals are encoded using the Manchester Biphase-L
technique. The signal is called synchronous serial because the clock information is embedded in the
serial stream. The protocol uses built-in error checking rules when processing data.
3.2 Fieldbus Function Blocks
The user application layer is programmed using software function blocks located in the device.
The function blocks provide the interface with the actuator and process, and the interface with the
network and control system.
The user layer in each device contains the following:
• One resource block
• One Transducer block for the inputs and outputs
• Function blocks for analog I/O and digital I/O
• Function Block for Proportional Integral Derivative (PID) Control
The Resource Block describes the hardware specific characteristics associated with the actuator and
its associated blocks; it has no inputs or outputs. Data in the Resource Block includes the following:
• Manufacturer’s name
• Device name
• Serial number
The Transducer Block represents local connection for the physical I/O. It connects function blocks
to the local inputs and outputs. It reads sensor hardware and writes to actuator hardware. The
Transducer Block executes as frequently as necessary to obtain good data from sensors and ensures
proper writes to the actuator without burdening the function blocks that use the data.