Mixer basic
Mixer basic| With
this function block a mixer control is implemented. |
Inputs |
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| FG |
Enable |
Optional. Not equal to 0 enables the mixer, the outputs
are driven. 0 closes the mixer for twice the run time and then switches
off all outputs. Not assigned: the mixer counts as enabled. |
| SW |
Setpoint* |
Flow setpoint to which control is performed. A setpoint of
0 switches the mixer off like a missing enable. |
| IW |
Actual value* |
Flow actual value. |
| KE |
Cooling |
Optional. Not equal to 0 switches to cooling mode. In
cooling mode the outputs are driven inversely; if the
actual value is greater than the setpoint, control is driven towards open instead of
close. Not assigned: heating mode. |
| RA | Feedback open | Optional. Feedback of the actuator for the output open. If it does not take on the value of the output within the monitoring time for feedback, the output is sent again and a fault is reported. Not assigned: no monitoring. |
| RZ | Feedback close | Optional. Feedback of the actuator for the output close, otherwise as feedback open. Not assigned: no monitoring. |
Outputs |
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| AU |
Open |
Output mixer open. |
| ZU |
Close |
Output mixer close. |
| PR |
Percent |
0-100% output. For mixers with
analog input. The value follows the actual travel time: if the mixer
opens for one full travel time, it goes from 0 to 100. It is sent at
the end of each travel pulse, not during travel. As long as a
deviation larger than the hysteresis is present, it keeps moving
with every pulse until the setpoint is reached. How fast this
happens is determined by PWM time, PWM min. pause and PWM max.
pulse - the P component no longer affects it and can stay at the
default value. The value is a calculation without feedback. It is stored and is available again after a restart or after a project has been transferred. If the mixer is moved by hand, the value is correct again only once the mixer has reached an end position, that is after it has travelled fully open or fully closed. |
| PU |
Pump |
Pump. A heating circuit pump can be connected here. It is
switched on when the enable is given and the setpoint is not equal to
0. When the actual value reaches the max. flow
temperature, the pump is switched off. The mixer position is
irrelevant here: at 0 % the mixer admixes entirely from the return,
which is not an absence of heat demand. Without circulation the flow
sensor behind the mixer measures standing water and the control loop
goes blind. |
| ST |
Info
Status |
Output is set to 1 when the
mixer is active. |
| IY |
Info
Y |
Output of the internal controller for diagnostic purposes. The output ranges from -255 (whole PWM time close) to +255 (whole PWM time open). |
| IP |
Info
PWM |
Output of the internal PWM timer -
time until next open/close cycle. |
| SR | Fault | Is set to 1 as soon as a feedback does not match the corresponding output. If the feedback follows, the output returns to 0 by itself. The mixer keeps controlling unchanged while a fault is present. |
| FZ | Error counter | Counts every detected monitoring error, including every repetition. After a restart of the controller the counter starts at 0 again. |
Parameters |
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| Run time |
Run time of the mixer. If the
enable is switched off, the mixer closes for 2x the mixer run time. |
|
| Gain P |
Gain for the internal controller.
With a higher value the mixer reacts faster. Important: With
too high a value the mixer starts to oscillate (constant
open/close control). |
|
|
PWM time |
Time for one open/close cycle. The
manipulated variable from 0-255 is mapped to this time. On time
is PWM time/255 * manipulated variable. |
|
|
PWM min. pause |
In this parameter a minimal pause time can optionally
be set (both outputs remain
off). This pause is observed at minimum, even if the
calculated off time would be shorter. After an open cycle the
pause should be at least as long as the flow sensor needs
to report back the current temperature. |
|
|
PWM max. pulse |
In this parameter a
maximal pulse time can be set. The internal controller is limited to
this maximum (maximal time for open), even if the
calculated on time would be larger. |
|
| Hysteresis |
Within this hysteresis the
temperature is considered reached and the mixer remains in its current
position. The hysteresis acts in both directions,
for example with a hysteresis of 1 the temperature
is considered reached within +/- 1 degree. |
|
| Max. flow temperature | When the flow actual value reaches this value, the output pump is switched off. The control of the mixer continues. | |
| Anti-blocking function | If this parameter is set, the mixer is started 1x per week
when the enable is 0. This is intended to prevent the mixer from
blocking when it is not in operation for too long. The function
is started on Sunday at 0:00h. The mixer travels the
mixer run time open/close, or the analog output is set to 0/100 percent,
and the pump output is switched on. When the anti-blocking function is active, 100 + step is output at the Status output.
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| Monitoring time feedback | Time within which the feedback must take on the value of the output. If the output changes again before that, the time starts over - during short PWM cycles there is therefore no monitoring, but there is during the pauses and while switched off. The time should be longer than the reaction time of the actuator and shorter than the PWM min. pause. | |
| Repeat send time | Interval at which the output is sent again after a fault. | |
| Max. repetitions | Number of repetitions per fault. After that nothing is sent any more, the fault remains until the feedback matches again. 0 = unlimited. | |