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en:automation:02-glossary:analog-inputs-hidden [2018/11/01 09:00]
jan_kozak [Measuring resistance]
en:automation:02-glossary:analog-inputs-hidden [2021/06/09 08:48] (current)
avsetula
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 ====== Analog inputs ====== ====== Analog inputs ======
-Analog inputs (AI) are for measuring analog values such as DC voltage, current and resistance. These values are produced by sensors which indicate multiple states such as thermometers,​ tensometers,​ distance meters, ​luxmeters ​etc.+Analog inputs (AI) are for measuring analog values such as DC voltage, current and resistance. These values are produced by sensors which indicate multiple states such as thermometers,​ tensometers,​ distance meters, ​lux meters ​etc.
  
 +----
 +
 +<​html><​span class="​kbBlueText">​More information about analog inputs can be found in specific categories:</​span></​html>​\\
 +
 +<​tile>​
 +| en:​hw:​007-patron:​description-of-io:​04-description-of-ai ​    | Patron ​            | :​en:​hw:​unipi-kb-icon-patron.png ​    |
 +| en:​hw:​01-axon:​description-of-io:​04-description-of-ai ​       | Axon               | :​en:​hw:​unipi-kb-icon-axon.png ​      |
 +| en:​hw:​02-neuron:​description-of-io:​04-description-of-ai ​     | Neuron ​            | :​en:​hw:​unipi-kb-icon-neuron.png ​    |
 +| en:​hw:​03-unipi11:​description-of-io:​04-description-of-ai ​    | 1.1 & 1.1 Lite     | :​en:​hw:​unipi-kb-icon-1.png ​         |
 +| en:​hw:​04-extensions:​description-of-io:​04-description-of-ai ​ | Extension modules ​ | :​en:​hw:​unipi-kb-icon-extension.png ​ | 
 +</​tile>​
 +
 +
 +/*
 ===== Analog inputs on Neuron and Axon ===== ===== Analog inputs on Neuron and Axon =====
-The functionality of AIs on Neuron and Axon is different on Group 1 and Group 2/3 and on Neuron extensions. ​+The functionality of AIs on Neuron and Axon is different on Group 1 and Group 2/3 and Neuron extensions. ​
  
 On Group 1, the analog input is capable of: On Group 1, the analog input is capable of:
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 </​WRAP>​ </​WRAP>​
  
-On Group 2 and 3 and on the Neuron extensions, the analog input is capable of:+On Group 2 and 3 and the Neuron extensions, the analog input is capable of:
   * measuring 0-10V DC   * measuring 0-10V DC
   * measuring 0-2.5V DC with higher precision   * measuring 0-2.5V DC with higher precision
   * measuring of 0-20mA DC   * measuring of 0-20mA DC
-  * measuring of resistance 0-100kOhm via 2-wire method +  * measuring of resistance 0-100kOhm via 2-wire method 
-  * measuring of resistance 0-2kOhm via more precise 3-wire method+  * measuring of resistance 0-2kOhm via more precise 3-wire method
  
 Changing between modes depends on the [[en:​sw:​00-start|software]] you are using, please follow the relevant tutorial. ​ Changing between modes depends on the [[en:​sw:​00-start|software]] you are using, please follow the relevant tutorial. ​
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 ==== Measuring voltage ==== ==== Measuring voltage ====
 ==== Measuring current ==== ==== Measuring current ====
-==== Measuring resistance ==== 
- 
  
 ===== Analog inputs on Unipi 1.1 ===== ===== Analog inputs on Unipi 1.1 =====
-The UniPi 1.1 has two analog inputs and they are only capable of measuring voltage in a range of 0-10V DC.+The Unipi 1.1 has two analog inputs and they are only capable of measuring voltage in a range of 0-10V DC.
  
 ==== Measuring resistance ==== ==== Measuring resistance ====
-To measure resistance from the UniPi 1.1's AI (ie. by using PT1000 thermal probes), it is necessary to add a resistor according to the following scheme.+To measure resistance from the Unipi 1.1's AI (ie. by using PT1000 thermal probes), it is necessary to add a resistor according to the following scheme.
  
 {{:​en:​automation:​02-glossary:​unipi_ai.png?​300|}} {{:​en:​automation:​02-glossary:​unipi_ai.png?​300|}}
-R_sens = the sensor itself 
-R_ref = the resistor 
  
-<WRAP center round tip 60%>  +   ​R_sens = the sensor itself 
- For reading temperature between 200-3800R (-200°C/​+800°C),​ a 1K resistor should be used to ensure ​the voltage will not exceed 10V.  +   R_ref = the reference resistor
-</​WRAP>​+
  
-The value at the AI is calculated using the following formula +There is also a input resistor inside of the AI with the value:
-''​R_sens (200) = 12V/969.7 + 200)*969.7 = 9.948''​ +
-''​R_sens (3800) = 12V/​(969.7+3800)*969.7 = 2.439''​+
  
 +   R_ai = 12200ohm
 +
 +<WRAP center round alert 60%>
 +For R_sens >= 200ohm, use R_ref = 1k. For R_sens < 200ohm, use R_ref = 10k
 +</​WRAP>​
  
 +The value at the AI is calculated from the voltage you read from the AI (V_ai)
  
 +             Vcc - V_ai     R_ref * R_ai
 +   ​R_sens = ------------ * --------------
 +                V_ai        R_ref + R_ai
 +                ​
 +The Vcc is the applied voltage (12V in the picture above).
 +*/