Manual

PoBlocks user manual (March 31, 2014)
43
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16.65. Control - On/off
Description
On/off
Inputs
PV (32-bit integer): Process Variable input (current value of the controlled variable)
SP (32-bit integer): Set Point
Outputs
Out (32-bit integer): On/Off controller output
Properties
Gain (Integer): Controller gain
Hysteresis (Integer): Half of the controller hysteresis - the difference between turn-
on and turn-off points . The controller turns on at PV > SP+hysteresis/2 and turns off
at PV < SP-hysteresis/2
Remarks
None
16.66. Control - PID
Description
PID (PID controller) is an implementation of a standard PID controller with filtered D-
part and output limits with integral anti-windup protection.
Inputs
PV (32-bit integer): Process Variable input (current value of the controlled variable)
SP (32-bit integer): Set Point
Outputs
Out (32-bit integer): PID controller output (in the range from Out min to Out max
Properties
K (Floating point): Proportional gain
Ti (Floating point): Integral time constant in seconds
Td (Floating point): Derivative time constant in seconds
Tf (Floating point): Derivative filter time constant - set to a fraction of Td
Out min (Integer): Output lower limitation (minimum output value)
Out max (Integer): Output upper limitation (maximum output value)
Remarks
When cycle time of the project is set to 0, PID block can not be used in the diagram
due to improper timing.
16.67. Communication - 1-wire R/W
Description
1-wire write and read operation block
Inputs
!CLK (Logic/clock): Inverted clock input signal
Write 1 - 10 (8-bit integer): Bytes 1 - 10 to write to 1-wire device
Outputs
Busy (Logic): Busy signal
Read 1 - 10 (8-bit integer): Bytes 1 - 10 that are read from 1-wire device
Properties
Write count (Integer, 0 to 10): Number of bytes to write to 1-wire bus
Read count (Integer, 0 to 10): Number of bytes to read from 1-wire bus
Remarks
Communication is started on falling edge of the !CLK input in order to support
chaining multiple communication blocks using busy signals - when one device
completes the communication session, its Busy signal goes from 1 to 0, which then
triggers a communication session on another block in the chain.