7/12/2013 11:39 PM | |
Joined: 12/1/2009 Last visit: 9/5/2024 Posts: 672 Rating: (147) |
Hi Juan. Mechatronic , I would try the diagrams below: S7-1200 (RS-485)----------------------- partner RS 485 (RxD/TxD+) <-------------------------+----->RDB (+) + +-----> SDB (+) (RxD/TxD-) <-------------------------+----->RDA (-) + +-----> SDA (-) S7-1200 (RS-422)----------------------- partner RS 485 TX+ <-----------------------------------------------------> RDB (+)
TX- <----------------------------------------------------->RDA (-) RX+ <----------------------------------------------------->SDB (+) RX- <-----------------------------------------------------> SDB (-) Unfortunate thedefinition of the polarity (+) or (-) differs with the vendors. My experiencewith the interfaces were mostly giving Aas negativeand Bas positive. That's whysmiffyis right when he says that you have to give it a try to swap between thepolarity to find it out for your device. Of cause only swapping on one side Good luck my friend |
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7/13/2013 3:01 PM | |
Posts: 559 Rating: (87) |
Please find the below link for modbus communication blocks for S7-1200 PLC. How do you establish a MODBUS-RTU communication with STEP 7 (TIA Portal) for the SIMATIC S7-1200? |
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7/13/2013 3:07 PM | |
Joined: 12/1/2009 Last visit: 9/5/2024 Posts: 672 Rating: (147) |
You are right smiffy, but wehave no detail about theinterface of his connected device. I interpret the second drawing as a 4 wire 485 which some vendors call422. So many times I read about this different namings but they mean the same. Let him try. |
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7/13/2013 4:19 PM | |
Joined: 12/1/2009 Last visit: 9/5/2024 Posts: 672 Rating: (147) |
Calm down smiffy, everybody knows that you are the expert and you have my deep respect. We are just trying to give solutionswhich automatizzandocan try out. And if it works out for himwhat's the problem?. He has nothing to lose except time. Best Regards. |
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