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7rots51
Joined: 17 May 2002
Posts: 1427
Helped: 14
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 19 Jul 2005 17:52 loadcell connection |
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Hello
How I can connect loadcell to s7-200 plcs(siemens)? Loadcell needs high precision ADC(more than 12 bits).
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khongai
Joined: 20 May 2005
Posts: 245
Helped: 5
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20 Jul 2005 11:45 s7-200 connection |
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you must use indicator weight and then depend on indicator weight you must select interface modul for PLC ( such as analog, BCD, RS232, ...).
Goods lucks.
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7rots51
Joined: 17 May 2002
Posts: 1427
Helped: 14
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20 Jul 2005 12:41 plc for load cell |
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| can I connect siwarex load cell modules to s7-200 PLC?how?
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sklux
Joined: 30 Jan 2002
Posts: 58
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20 Jul 2005 17:16 plc s7 module connection |
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Connecting load cells must be done with the right material :
a load cell is basically an high precision resistor.
So a Δ wheight gives a Δ resistor. You can measure this with a millivoltmeter.
Of course the wiring of your loadcell to your plc as a direct influence on your
measure.
If you really want o use a S7-200 try to find a module that convert the measure of the
wheight to a 4-20 mA signal which is easier to handle with a PLC.
Try Metler Toledo they are specialists on the wheighing field you ll maybe find such
module
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20 Jul 2005 17:16 Ads |
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7rots51
Joined: 17 May 2002
Posts: 1427
Helped: 14
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21 Jul 2005 11:58 siwarex ma |
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Hi sklux:
I know that there are some loadcell modules that convert weight to 4-20mA,
But the ADC modules of s7-200 have 12 bit resolution ,and in real world only 8 bits of them are useful.so I can not use s7-200 ADC(AI) modules!
This is a very weak point for siemens that not suport high presicion bridge sensors!
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sklux
Joined: 30 Jan 2002
Posts: 58
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25 Jul 2005 1:02 connecting s7 200 |
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In fact S7-200 is low range PLC of Siemens. You could find certainly more accuracy
on S7-300/400. So is Profibus a standard on the industry, you may find an interface
that can handle the connection with the load cell and give the result as a profibus slave.
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7rots51
Joined: 17 May 2002
Posts: 1427
Helped: 14
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27 Jul 2005 14:21 siwarex load cell s7 200 |
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I got this link from siemens support,use siwarex modules:
"It is possible to use the Siwarex U with S7 200.
Please look in the internet under the following address:
http://support.automation.siemens.com/WW/view/en/1853353
Additional I am informing you that Siemens works on a new module
especially for S7 200.This new module will come to market in the next year.
If you have further questions don't hesitate to contact me again."
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