Siemens SIMATIC S5 Manual page 9

Technical Description
The various functions of the controller module are processed by the microprocessor:
– measured value acquisition via multiplexer and ADC
– measured value processing according to the control algorithm, (system error formation,
manipulated variable calculation, self-optimization)
– monitoring limit values of measured values and generation of interrupts
– output of manipulated variables via registers and output drivers
– calculation of the temperature compensation value according to the reference junction
temperature (Pt 100)
– comparison of an analog input value with a digital value (limit value monitoring disabled)
– controlling the interface to the S5 system bus
Fig. 1.3/1 Block diagram of the temperature controller 244-3AA22
The module can be operated as a switching two or three step controller with percentage output
according to the control algorithm stored in the EPROM.
The controller action (P, PI, PD, PID) is selected by inputting the appropriate parameters. Data
(setpoints and parameters) is exchanged between the CPU and the temperature control module
by means of 64 messages each with a length of 32 bytes.
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IP244
C79000–B8576–C859–02