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User Manual
Piccolo Range
6. Controller Block Diagram
The block diagram shows the simple function blocks which make up the controller. Where applicable, each block is
represented by the ‘P’ code as described in the previous section.
The quick start code and the ‘P’ codes set the parameters to match the hardware.
Inputs
Control
Processes
Outputs
Sensor
eg thermocouple, RTD,
mV, 0-20mA, 4-20mA
Sensor Input
P1 to P6
Setpoint
Control
P7 to P8
PID/onoff/Tune/Auto-Man
Output 1 (OP1)
eg Heat
P11
Output 2 (OP2)
eg Cool
P12
Digital Input 1
P51
Alarm(s)
P21 to P29
Output 3 (OP3)
eg Retransmission
or alarm
P13
To plant
actuator
devices
Digital Input 2
P52
Timer
P41 to P44
Output 4 (OP4)
eg Alarm
P14
Current
Transformer
Input
P31 to P33
CT Alarm setting
P31 to P33
Digital
Communications
P61 to P65
RS485
The Temperature (or Process Value, PV) is measured by the sensor and compared with a Setpoint (SP) set by the
user.
The purpose of the control block is to reduce the difference between SP and PV (the error signal) to zero by
providing a compensating output to the plant via the output driver blocks.
The timer and alarms blocks may be made to operate on a number of parameters within the controller, and digital
communications provides an interface for data collection, monitoring and remote control.
The way in which each block performs is defined by its internal parameters. Some of these parameters are available
to the user so that they can be adjusted to suit the characteristics of the process which is to be controlled.
These parameters are found in lists in both Operator Level 1 and Operator Level 2 where Level 1 is a sub-set of
Level 2.
The above block diagram applies to P108 and P104 controllers.
For P116 Output 3 and Digital Input B are not present.
62 Part No HA031260 Issue 1 May -12