MODBUS Communication Between S7 PLC and National Instrument Master Software
Cannot get MODBUS communication going between National Instrument master and S7. Is it a hardware problem?
By Chris A on 29 March, 2015 - 8:40 pm
If the serial port is indeed unable to connect, either through an application or driver problem,...
By rnarias on 23 March, 2015 - 1:05 pm
grateful for your reply. yes, the S7 has a Modbus slave port that talks on RS-485 in DB9. it is...
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By Roy Matson on 27 March, 2015 - 4:38 pm
If the slave sent your request back you must be getting close, to send it back it must be receiving...
By Koen Verschueren on 27 March, 2015 - 3:01 pm
Hi, Your telegram seems to be OK so this should work. Since you are receiving the same...
By Koen Verschueren on 25 March, 2015 - 2:22 pm
Hi, If you receive no response you have a problem with wiring and/or communication settings....
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Posted by Charles Casalie on 13 February, 2015 - 11:45 am
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Implementing modbus on microcontroller but encountered a very puzzling issue
By Lynn August Linse on 27 February, 2015 - 5:07 pm
Also watch out for flow-control, as if your 'driver' assumes XON/XOFF, then sending any Modbus...
By Curt Wuollet on 27 February, 2015 - 2:32 pm
> A datascope program lets you put a PC on the wire between the master and slave and lets you...
By Curt Wuollet on 23 February, 2015 - 10:02 pm
You shouldn't be too fast to decide A implies B. A different command can have different overhead. ...
By Curt Wuollet on 22 February, 2015 - 7:00 pm
Sounds a lot like a timing issue. I'd try a datascope program so you can see the effect of...
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By Chris A on 22 February, 2015 - 7:09 pm
Think of RS-232 as the communication interface and Modbus RTU as the communication language....
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By Lynn August Linse on 17 February, 2015 - 10:06 am
The closest think I have seen to a 'standard' doc format is the renewable energy work done by...
By Christof on 17 February, 2015 - 6:58 am
thanks for your answers. This is what we now intend to implement: - gateway would be a slave ...
By Lynn August Linse on 13 February, 2015 - 9:38 am
At a minimum, I would suggest this: 1) all data available as 4x/holding registers, read by func...
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By Ekanki Sharma on 20 February, 2015 - 6:43 am
Sir I am looking for, whether IEC 61850 standard works on TCP/IP. Is there any similarity...
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By Cjohnson44 on 16 February, 2015 - 11:02 am
I tried the null modem configuration less the resistor and swapped the Tx and Rx lines and I am now...
By Curt Wuollet on 15 February, 2015 - 10:56 pm
RS232 has a lot of fiddly bits compared to RS485. A full implementation can use a lot of signals....
By Cjohnson44 on 15 February, 2015 - 6:52 pm
Data bits is set to seven, even parity, and 1 stop bit. I have a null modem cable I can try and I...
By Curt Wuollet on 15 February, 2015 - 11:25 am
RS232 is point to point. and and doesn't use a terminating resistor. It sounds like you are using...
By Cjohnson44 on 15 February, 2015 - 2:43 am
> Connect the +12V to DTR. I have tried that as well as jumping the DTR to the DSR, without...
Need Help for Final Year SCADA Project Soon Please
Posted by chitra barvekar on 13 February, 2015 - 9:54 am
Need help connecting SCADA (laptop) and microcontroller board using modbusa3 protocol
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