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S7-1200 and temperature sensor SMT-160

Created by: alda2 at: 10/3/2011 3:56 PM (2 Replies)

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10/3/2011 3:56 PM	Rate (0)
alda2 Posts: 1 Rating: (0)	Hallo, I'm new user here on the forum and I'm searching for working ( if exist ) solution, how measure temperature with temperature sensor SMT-160 connected to PLC S7-1200 ( CPU 1212C ). Signal from SMT-160 is PWM - so I need to now how long is "on" signal an how long is "off" signal to calculate measured temperature. Is there somebody with experience with this sensor ? I checked a lot of posts, but I can't find information about working solution. Thanks for help Alda for more information about SMT-160 please check attachment Attachment smt_smt160.pdf (184 Downloads)
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10/3/2011 5:16 PM	Rate (0)
watr_fallr Member Joined: 7/22/2011 Last visit: 5/15/2019 Posts: 3 Rating: (0)	I can make some comments about your electical components / issues. For the system application / user code I think someone else should probably help. I believe it is possible to use some of the HSC functions on the CPU/Signal boardinputs to measure the duty cycle. The temperature sensor you have selected requires 5V and the S7-1200 does not provide 5V. If you have this in your system there maybe some possibilities to use a SB1221 DI 4x5VDC, 200kHz (6ES7221-3AD30-0XB0) to bring the output of the sensor in to the S7-1200. This Signal Board (SB) however is not TTL/CMOS compatible. It is intended to be used with open collectoroutputs from encoders. By this it means that the inputs are sourcing inputs (load resistor from power supply to the input). This also means that your output being on will be interpreted by the SB as off. The other concern is the temperature sensor has an output impedance of 200 ohms and the input has an impedance of ~ 330 ohms (5V / 15mA). These two impedance may form a resistor divider and make it such that the input does not get enough voltage to sense the on or off voltage. You may have to try it to see how much margin you have. If you don't have 5V in your system you may want to consider using an RTD / Thermocouple SB instead as they can measure temperature. Cost of a 5V PS SMT160 sensorversus SB & RTD/TC sensor.

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5/23/2016 10:57 AM	Rate (0)
Min_Moderator Platinum Member Joined: 9/3/2014 Last visit: 3/13/2019 Posts: 4766 Rating: (122)	New question published by AutoGen_948162 is split to a separate thread with the subject Can i connect tamperature sensor without rtd module?. Best regards Min_Moderator

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