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TIP: S7-1500 – Thermocouples -Compensation by means of dynamic reference temperature
Created by: Denilson Pegaia at: 4/2/2013 5:22 PM (0 Replies)
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| 4/2/2013 5:22 PM | |
Joined: 9/23/2005 Last visit: 11/4/2024 Posts: 4351 Rating:
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The analogical processing of thermocouples signals (e.g. by 6ES7531-7KF00-0AB0) needs an information of the temperature in the “cold size” of then. In S7-1500 there is five ways to do it: 1 – Internal reference junction: reference junction is measured using an integrated sensor in the analog module 2 – Reference channel of the module: reference junction temperature is determined using an external thermal resistor 3 - Reference channel of group 0: channel 0 is used as reference 4 – Fixed reference temperature: the reference junction temperature is set as module parameter 5 - Dynamic reference temperature: reference temperature is set by user program (e.g. from other analogical module). These possibilities are decrypted detailed in the manual “S7-1500, ET 200MP, ET 200SP Analog value processing Function Manual” (http://support.automation.siemens.com/BR/view/en/67989094). For the option 5, dynamic reference temperature, it is necessary that the user program the call of the WR_REC block to set the desired value to the module. The WR_REC needs a REQ command (e.g. follow logic for edge evaluation), the module ID (hardware identifier, e.g. by symbolic name set), the respective index (192 to 199, respectively to the channel) and a data record with the value. You can get information about the module parameters from the online help of STEP7 and in the module manual (http://support.automation.siemens.com/BR/view/en/59193205). Follow is attached a sample program that set the fix value (25 Celsius) to the channel zero of the analogical module. AttachmentC:\Users\z0008iwv\Documents\Bluetooth Exchange Folder\S7-1500 dynamic analogic reference.zip (1125 Downloads) |
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