Hi,
I have a flowmeter connected to wago pfc300, this one : https://www.burkert.com/en/Media/plm/DTS/DS/ds8020-standard-eu-en.pdf?id=DTS0000000000000001000011076ENAA
I think it is connected through digital input ?
And my question is : How can I read the digital inputs in CodeSys ?
I already added the inputs (analog & digital) :
I mapped a variable in the first k-bus (75x_8DI) (I wonder DI is for digital input) but the value show 0. I tried the same in the second k-bus also.
Is the variable used in the PLC program ?
If not, by default, the variable won’t be refreshed if not used.
Do you want to detect pulse ? If so you have to make sure pulse are long enough to be detected by the digital input ( depending on input filter) and you’ll have to use a rising trigger (R_TRIG) to detect the input and increase a counter.
Hi,
What do you mean by “use” because I only declare the variable like testinput; in the programming section.
And yes I want to detect pulse
If it’s in the programming section then it’s enough.
So in your case you probably don’t see the pulse of the flowmeter between 2 “refresh” of CODESYS.
Try something like that
oR_TRIG : R_TRIG;
dwCounter : DWORD;
oR_TRIG(IN:=testinput.0);
IF oR_TRIG.Q THEN
dwCounter := dwCounter+1
END_IF
You’ll probably want to multiply by the pulse weight, specified in the datasheet (1 pulse = 50 L)
Make sure the pulse frequency fits the digital input specs.
Standards DI have a 3.0 ms input filter.
We also have DI with 0.2 ms input filter
If it’s not enough we have dedicated pulse counter inputs. (750-404 for instance)
here is the spec of my digital input :
Name 75x-8DI
Fabricant : WAGO
Catégories :
Type : 32776
ID: 8801_075xDigital
Version: 2.0.0.13
Description : 8 DI Generic
075x-8DI
You need the part number (750-430 ?)
If the LEDs are on and the input readings are fixed at “3” (as shown in your previous screenshot) , that means you have a broken wire connection or your input signals are <4ma. Make sure your flow meters have power and are providing a 4-20mA signal. This module is not going to directly provide loop power for 2-wire devices.
Thank you, I will explore this path and give an update
The flowmeters are connected to a transmitter so there is a continous power provided : https://www.burkert.com/en/Media/plm/DTS/DS/ds8619-multicell-eu-en.pdf?id=DTS0000000000000001000130448ENX
Please be more specific about which flowmeter is used and on which channel of which I/O module it is connected. On your first question it was on a digital input and now you mention an analog module, it is confusing.
The system includes Bürkert Type 8020 flowmeters (generate pulses), a multiCELL 8619 display (displays flow values well on the screen), and WAGO modules. The 8020 flowmeters are connected to the module 750-455 (analog) at the addresses %IW10-13, but the problem is that the values are fixed at ‘3’ (signal < 4mA).
Hi,
a value of 3 and red LEDs mean there is a failure on the corresponding channel. This is mostly a broken wire/connection.
So, check
For the wiring check, check also if the planner has the connection correctly planned, as the multicell 8619 has to be connected like a 2-wire transmitter to the WAGO module.
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