Yokogawa YVP20S - Manual (Page 31)

5-2
<Toc> <Ind> <5. FOUNDATION FIELDBUS OVERVIEW>
IM 21B04C50-01E
5.1.1 P & I D
Figure 5.2 Piping and Instrumentation Diagram
The piping and instrument diagram (Figure 5.2) shows, in schematic form, the physical
devices and indicates the measurement and control functions that reside in each device.
The coolant flow transmitter, FT 102, has only a transmitter function, but the coolant flow
control valve, FV 101, has a PID control, two limit switches (DI blocks) and an AO block
all located in the YVP valve positioner. The flow of control information between devices
is indicated by dashed lines. The DI blocks, ZSL 101 and ZSH 101, serve as low and
high stem position limit switches, respectively.
Liquid level is controlled by a remote controller LC201 (to demonstrate Remote
Cascade operation). The controller receives the process measurement from level
transmitter LT 202. The PID control regulates the valve LV201 (an YVP positioner with
an Analog Output Block, and 2 DI function blocks. The DI blocks, ZSL 201 and ZSH
201, serve as low and high stem position limit switches, respectively.