Programming Temperature AI RTD in PLC Logo!

The Analog Input RTD are values from Thermocouples received by PLC RTD Modules and sended by PT100, This may be the best way to measure and Control Temperature, Thermocouple (PT100) is a robust device that supports high temperatures and aggresive enviroment, and better is easier to scale than Analog Inputs!

OFF => -50°C

Simulating 4 different values from -50 to 200 °C , let's turn on Q1 when T° >50°C

First, We must to know these concepts:

RTD Modules: There are the expansion modules used by PLCs and are used as the best way to measure Temperature in a PLC, this module works directly connected to a PT100 (very used)

Thermocouple or PT100 There are Sensors designed to measure Temperature, use two dissimilar electrical conductors forming an electrical junction, we think is the most reliable Temperature Sensor used in industries and other industrial enviroments, in a PLC PT100 always must to be connected in a RTD Module, CPU almost never has a RTD Input integrated

Must Knowledge

Industrial Command
Computation
Electricity
Basic English
First Time with Logo!

MAIN SUMMARY
STEP 1: Necessary Elements
STEP 2: Necessary Hardware
STEP 3: Wiring and Technical Details
STEP 4: Programming PLC (include Video too)
STEP 5: Upload Program to Logo!
STEP 6: QUESTIONS & ANSWERS

STEP 1 : NECESSARY ELEMENTS

First we must to have all components and PLC in LADDER

The Programmable Relay PLC Logo! need a Software to make the Program that control all our process, so we need these elemments:

Notebook or Portable Computer with CD-USB o CD
PLC Logo! V8 Siemens
Communication Cable Ethernet Cat5e o higher
Software PLC Logo Siemens; Logo Soft Comfort V8.0 or higher
Wiring in 220VAC (We use Logo! 220VAC)

NO problem if we dont have the Original CD, we can Download DEMO VERSION Here Download fast! from Siemens WebPage in "Demosoftware" if we have this demo, we may simulate and create a lot of control projects really perfect to practice

PASO 2: NECESSARY HARDWARE

Measure Temperature in PLC Logo! Have some devices to work correctly

IDENTIFY ALL ELEMENTS

CPU PLC Logo! 220VAC (in this case)
Expansion Module RTD (AM2 RTD) Watch Model
Switching Power Supply 220VAC / 24 VDC
PT100 or Thermocouple 3 wires
Shielded Cable +4xCables 1.0mm2

We have some advantages working with RTD Modules to Meaasure Temperature, measure temperature is very important in process of any type

Easy configuration in Software
Easy Wire in PLC-RTD Module and PT100
Thermocouple is capable to work in extreme Temperatures, an Analog Sensor can't support highest temperatures
Very reliable and less Sensitives than Analog Transmitters, of course measuring Temperature

PASO 3: WIRE AND SPECIFICATIONS

Wire a Thermocouple PT100 and PLC is simpler than AI

We can see the examples from Siemens Webpage connecting 2-3- 4 wires PT100 to RTD Module, and other side we have our circuit connecting a 3-wire PT100 in a PLC Logo! and Expansion Module

VERY IMPORTANT

RTD Input Modules in almost cases are powered by 24VDC

Wiring is exactly as the image, RTD Module is powered by 24VDC and PT100 is connecting directly to RTD AM2

This way is easier to wire than Analog Input

Remember consider Ground GND in all devices that needed

The better and more Robust way to measure Temperature may be using RTD and PT100 (Thermocouples)

PASO 4: PROGRAMMING PLC

Now Let's configure Input Temperature RTD

Access to Logo Soft Comfort and start to create the program with follow blocks:

Add block and before to Configure let's Know what means each one:

AI1 This is RTD REAL Input, it means this Input comes directly from the Sensor PT100 3-wires Connected in RTD Module Channel 1

SF001 Analog Amplifies will be use for Scale RTD Value in Real Temperature Value (remember an Amplifier is just for monitoring, can't activate digital outputs)

SF002 Analog Thershold Trigger also can Scale Signal RTD in Real Value, Configure Analog Signal Input and then activate ON - OFF in real Temperature!

SF002 (Digital Contact): When reach the values configurated ON and OFF in SF002, The Contact will activate or desactivated, from AI1 (Channel 1 RTD Module) comes signal and Scale and define ON or OFF very easy

Q1: Normal Output used now just example, in this moment we must to know all about these concepts

To Learn Better we recommend to visit Programming First Time a PLC Logo! CLICK before understand better Analog Inputs

Configuring RTD Input Blocks:

The Parameters to configure are simple:

Sensor PT100/PT1000 choose this option, and by default are assigned predetermined value, almost all configuration is OK

Celsius o Farenheit Degree You have the option of choose the measure degree in both options

Resolution Here you can choose adjust minium and maxium measurement range, between -500/2000 to value -50/200

Analog Threshold Trigger Too can Scale parameters from RTD PT100 and configure a Output in "ON" or "OFF" this is the simplest way to activate or not a Output, for Output you use a "Digital Make Contact"

Differences Between RTD and Analog Input 4-20mA are the simpler way to configure, you can add more other Sensor and Modules and Configuration is not difficult

SIMULATING RTD INPUTS

OFF => -50°C

Simulating 4 values from -50 to 200 °C, Turn ON Q1 if T° >50°C

VIDEO RTD SIGNALS

NOTE: In case you are using PLC Logo 12/24 RCE (24 Volts) these PLCs have enabled AI to use in CPU (0-10V), to be more reliable that "AI1" is the Input of Channel 1 in RTD Module GO to File -> Properties -> I/O Settings -> Enable 0 AI

QUESTIONS & ANSWERS

HERE THE ANSWERS MOST IMPORTANTS:

Where Can Download Logo Soft Comfort! The Software of PLC Logo? and Buy Original CD?
For the Version DEMO go to Siemens Webpage here or you try in the above external links of Step 2 Here; It Costs around 70 USD (without upgrades) and you can get it in a external company Buy in Automation24 this software may be installed in many computers

I Have a PLC Logo! 24V 24RCE and my RTD Input Module AM2-RTD don't work?
It may happens is not strange, because PLCs Logo! powered 24V have incorporated 2 or 4 Analog Inputs (in 0-10V) but it must to be configurated, to see configuration go to Logo Soft Comfort! -> File -> Properties -> I/O Settings -> "Enable 0 AIs" ; it means no one AI in CPU is configurated, so the first "AI1" will be on RTD Module

How can I Understand fast how RTD Module and PT100 Works?
If you have read the section Programming Analog Inputs PLC Logo! this section is easier to learn
1. The Sensor to measure is a PT100 or Thermocouple
2. Need a RTD AM2 Module to work with PT100 and PLC
3. Power 24VDC the RTD Module
4. For a better Measure the Sensor PT100 must to be directly connected to RTD Module avoiding link wires
5. Scale values is easier and simpler you must to create Analog Contact AIx and link to a block, then in block select PT100/PT1000, most used Blocks are Amplifier and Threshold Trigger
6. Wiring must to be right connected in Control, Power and Ground
7. Details explainded in STEP 3 HERE

Why Can't Connect with my PLC Logo?
The Communication with PLC Logo! is by ETHERNET (TCP/IP); you should change your Sub-network number in your computer, remember Logo! comes with 192.168.1.x or 192.168.0.x must to try with both options

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Programming Temperature AI RTD in PLC Logo!