I'm trying to use an OPTA to manage an HVAC system with 6 temperature sensors (initial plan was PT1000) and 2 flow sensors output 4-20ma).
unfortunately the opta analog expansion handle only 2 PT1000 sensor, and is a non sense buy 3 expansions.
I evaluated the ds18d20 that I applied in the past to arduino, but discovered that input are only analog and did not handle this sensor (confirmed also in a post by an arduino spokesman)
Did you have some alternative, reliable, suggestions?
Hi, for the temperature sensors try https://www.sontay.com/en-gb/ they have a wide range of temperature sensors with 0-10V outputs ideal for the OPTA. For the flow sensors try using a convertor from 4-20mA to 0-10V. I have used these in the industrial arena for 15+years with various PLC products.
Hi @igorte ,
Arduino Opta offers inputs that are configurable as digital or analog. Please take a look at the Features section of the Datasheet.
On the other hand, you can check the DS18B20 sensor option with Arduino Opta. For this you can use the following library OnewireNg library . Please take a look at the DallasTemperature example sketch.
Best,
Hello @Hm_pro , can you please elaborate which PIN on the Opta are suitable to connect the DS18B20. Thanks
According to what i read in the past, on OPTA is not possible to use digital sensors. Digital input seems to be not suitable for these frequencies.
If i'm wrong I hope to receive a detailed help to apply them.
Igor
The 0-24V industrial standard digital inputs on the Opta are incompatible with 3.3V or 5V digital sensors.
Use industrial standard PT1000 sensor modules for your HVAC system.
Ok, thanks both @jremington and @igorte . Anyway, let's hope the expansion module for the PT1000 sensor will be released as soon as possibile
While you are waiting, take a look at the industrial standard PT1000 modules already on the market.
@jremington in which way you usually read them, by the modbus i guess?
Hi,
@jremington why you write 0-24 input? according to technical specification the opta input is 0-10V and the power supply may be 5V with a dedicated power supply. I read many times that DS18B20 is not suitable, but not clear to me WHY.
@alphagamma alpha About PT1000, is not possible a direct connection to OPTA base module, because it allow only 0-10V connection. It will be possible with a converter that has a cost (10 to 80€).
OPTA analog expansion will arrive on the shop not early than April ( information received by Finder ,customer support)
The OPTA analog expansion will accept only 2 PT100/PT1000 on each expansion module (info presented by Finder in a webinar). Since I need 6-8 thermal input, I probably will use a Datexel DAT8019 to avoid to use many components.
You are quoting the analog operational range. The digital operational range is 0-24V. Clearly, you need to become more familiar with the operating characteristics of the Opta, and industrial equipment in general.
Thanks for your clarification
Excellent response.
So. If we raise the GND from 0 Volt to 2.5 Volt (ie. by a 2.5 Volt Zener Diode) and lower the 10 Volt to 7.5 Volt (ie. by a 2.5 Volt Zener diode), then the DS18B20 would be in the right interval, is that not true???
This is based on that you noted VIL max 4.46 Volt, and VIH min to be 6.6 Volt, because, with a lift of 2.5 Volt from GND, I guess VIL would then become 1.96 Volt, and VIH would become 4.1 Volt - meaning, that the DS18B20 just COULD (maybe) be able to operate??? Question is then, if these "inputs" can be configured also as outputs???