# PLC s7 200 problem conrolling inverter [VFD]



## JRaef (Mar 23, 2009)

sayedengg said:


> HI everyone, I have come across problem with PLC s7- 200 ,which has got two modules em 221 and em 232. This plc system controls various conveyors and speed regulation of the products between differnet conveyors.
> The main problem is that the PLC is not able to output the inverters (VFDs) that control the conveyors. The voltage across the terminals in the PLC module [ EM 232 CN] that controls[ control signal ] inverters is constant,i.e, 10 Volts DC and hence drives are running at high constant speed instead of varying speed. Also, I have checked the wiring connection and the inputs of the plc; they are fine.
> It was fine for almost 2 years + and now when the operator started machine, the drives are running speedly. I would appreciate if someone can help in how to get around the problem.
> If there is anymore details need , I would surely help.
> ...


The CN at the end of the part numbers indicate that those Siemens PLC components were made in China and designed to be used *only* in China for domestic consumption, _*not*_ exported. There are also a lot of Chinese OEMs exporting machinery and/or suppliers selling these PLCs dirt cheap over eBay and other internet sites in flagrant violation of the rules with Siemens, but they don't care. To make sure that doesn't affect their world-wide sales, Siemens has embedded code that makes it so that Siemens programming software used outside of China will not work on those units. What can happen is, a user outside of China gets the software with it, but the first time they upgrade the software with Siemens, it changes to the non-Chinese version and begins creating errors in the operation of the PLC. Happens all the time (I used to work for Siemens), but it is the result of Chinese OEMs and resellers not playing by the rules they agreed to when Siemens allowed them to make and sell the S7-200's in China for a lot less than they charge for them everywhere else in the world. 
Talk to your OEM or go buy a new S7-200 and the I/O modules from a supplier in India where you are...


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## nolabama (Oct 3, 2007)

The China man has no concept of intellectual property.


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## sayedengg (Mar 27, 2012)

Thanks for repling guys, I know the OEM is china man but now the problem has occured; we have to get it resolved up soon. About buying new s7 -200 will mean to program once again. I was wondering if we can use any version of s7-200 software to connect china s7-200 plc ?


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## JRaef (Mar 23, 2009)

sayedengg said:


> Thanks for repling guys, I know the OEM is china man but now the problem has occured; we have to get it resolved up soon. About buying new s7 -200 will mean to program once again. I was wondering if we can use any version of s7-200 software to connect china s7-200 plc ?


No, that exactly what you CAN'T do. But if you buy new legitimate S7-200s now, the software you have, assuming it was upgraded by Siemens, should load and work. You should speak to Siemens in your country.


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