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--- en:automation:02-glossary:analog-inputs-hidden [2018/11/02 07:55] – [Measuring resistance] jan_kozak
+++ en:automation:02-glossary:analog-inputs-hidden [2025/10/10 11:11] (current) – added edge ofojt
@@ Line 1: / Line 1: @@
 ====== 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:004-edge:02-description-of-io:04-description-of-ai    | Edge               | :en:hw:unipi-kb-icon-edge.png       |
+| 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 =====
-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:
@@ Line 13: / Line 28: @@
 </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 0-2.5V DC with higher precision
   * measuring of 0-20mA DC
-  * measuring of resistance 0-100kOhm via 2-wire method
+  * measuring of resistance 0-100kOhm via a 2-wire method
-  * measuring of resistance 0-2kOhm via more precise 3-wire method
+  * measuring of resistance 0-2kOhm via a more precise 3-wire method
 Changing between modes depends on the [[en:sw:00-start|software]] you are using, please follow the relevant tutorial.
@@ Line 24: / Line 39: @@
 ==== Measuring voltage ====
 ==== Measuring current ====
-==== Measuring resistance ====
 ===== 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 ====
-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|}}
-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 = 9.948V''
-''R_sens (3800) = 12V/(969.7+3800)*969.7 = 2.439V''
-When the -200°C temperature is measured, a 9.948V voltage is present on the AI, while with the +800°C temperature the AI voltage will be 2.439V. To verify those values, please check the documentation of your sensor.
-Note: Please keep in mind the ability of UniPi 1.1's architecture to precisely measure voltage is limited at voltages up to 0.05V. For our showcase sensor, the resulting deviation could be up to +-50°C. If a more precise measurement is required, change the R_ref value accordingly.
-If the R_sens value does not match the requirement, you need to change the R_ref setting. The R_ref value is calculated using this formula
-''Rx = (R_ref*12K8)/(R_ref+12K2)''
-When setting the R_ref, please ensure that at maximum/minimum resistance the voltage at AI+ will not exceed 10V or decrease below 0V.
+   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).
+*/