Operation
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6 Operation
The controller has two operating modes: Control and Configuration (see sections 7 and 8).
6.1
Block diagram
Fig. 6.1 Block diagram
An analog input signal from the resistance thermometer or thermocouple is converted
according to sensor curve into a standard signal. The measured value is digitalised, ana-
lysed and processed in accordance with the set parameters. The results are saved in
memory registers according to the Table C.2. For the complete parameter list refer to the
Table B.1.
6.2
Input sampling
Inputs are sampled cyclically. An input is included into the sampling list when a signal
type is selected in the parameter
in-t
(PL-1 group). The input is excluded from the list if
the parameter
in-t
is set to OFF.
The order and the rate of sampling for each input are defined by priority which can be set
as a number from 1 to 8 in the parameter
Prt
(PL-1 group). The highest priority is 8.
6.3
Cold junction compensation
The cold junction compensation provides a precise temperature measurement with ther-
mocouples. A reference junction sensor is located near the input terminals. To enable the
function set the parameter
CJ-.C
(PL-0 group)
to ON. This setting is effective for all in-
puts.
Other filters and corrections for individual inputs are described in sections 6.4 and 6.5.
6.4
Linear scaling
To scale the linear signal (current or voltage) the measurement limits must be set. Pa-
rameters
Ain.L
“Signal lower limit” and
Ain.H
“Signal upper limit” should be set in physi-
cal units.
If
Ain.L
<
Ain.H
, then
𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑣𝑎𝑙𝑢𝑒 = 𝐴𝑖𝑛. 𝐿 +
(𝐴𝑖𝑛. 𝐻 − 𝐴𝑖𝑛. 𝐿) ∗ (𝑆
𝑖
− 𝑆
𝑚𝑖𝑛
)
𝑆
𝑚𝑎𝑥
− 𝑆
𝑚𝑖𝑛
If
Ain.L
>
Ain.H
, then