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4
Functional Description
NOTE
Please refer to the description of the complete operating menu in Section 8 for a detailed
description of the individual characteristics of the DULCOMETER
®
D1C controller!
4.1
Operating Menu
The D1C controller permits settings to be made in two different menus. All values are preset and can be
changed in the
complete operating menu
.
The controller is delivered with a
restricted operating menu
so that the D1C controller can be used
effectively in many applications from the very onset. If adaptations prove to be necessary, all relevant
parameters can then be accessed by switching over to the complete operating menu (see “General
Settings”).
4.2
Access Code
Access to the setting menu can be prevented by setting up an access code. The D1C controller is supplied
with the access code 5000 which permits free access to the setting menu. The calibration menu remains
freely accessible even if access to the setting menu is blocked by the code.
4.3
Control
The D1C can operate as a proportional controller or as a PID controller - depending on the device version
(see identity code) and the setting.
The controlled variable is recalculated once a second. Control procedures which require rapid correction of
setpoint deviations (less than approx. 30 seconds) cannot be processed with this controller. The cycle
times must be taken into consideration when activating solenoid valves (pulse length) in the same way as
their running times when activating servomotors (3-point).
Via the control input pause, the control function (selection of controlled variable) can be switched off. The
calculation of the controlled variable starts again after cessation of "pause".
4.4
Feed Forward Control
The D1C controller can process a signal of a feed forward control. Depending on the device version (see
identity code) and the setting, this signal can be obtained in any form of a 0–20 mA or 4–20 mA signal or as
a digital contact signal with the maximum frequencies 10 Hz or 500 Hz.
This signal can be used, for example, for flow-proportional metering (multiplicative effect) or feed forward-
dependent basic load metering (additive effect). The result of control variable calculation from the
proportional or PID control is multiplied by or added to the feed forward signal. A multiplicative feed forward
variable at the level of the set rated value carries over the calculated controlled variable unchanged into the
control variable:
Control variable = Feed forward variable/rated value x calculated controlled variable
During start-up, the zero point has to be checked. The feed forward control is not designed for switching off
permanently the actuating variable (signal
≈
0).
An additive feed forward variable at the level of the rated value results in maximum control variable:
Control variable (max. 100 %) = (Feed forward variable/rated value x
max. control variable) + calculated controlled variable
4.5
Error Messages
Error messages and information are indicated on the bottom line in the permanent display 1. Errors to be
acknowledged (acknowledgement switches off the alarm relay) are indicated by the " ". Errors/notes
which still apply after acknowledgement are indicated alternately. During correction variable processing
(temperature for correction of pH-value), the value is indicated in the same line as the error/note. Faults
which are rectified of their own accord due to changed operating situations are removed from the
permanent display without the need for acknowledgement.
BA_DM_183_10_10_EN.p65
28.10.2010, 11:44 Uhr
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