Can I use CPU 115u 944B in instead of 115u 944 ?

Hello, 

The thing is that I don't have to much experience with siemens and I have a problem, I think the problem is the CPU, because all the red lights are ON (  ST,   QV, ZY, BA  )   I already tried overall reset several times and tried other way that I read in the forum, Turning off the entire power and remove the batteries, wait 10 minutes and tried to read the eprom. 

The program should be in the eprom.

The CPU with the problem is 115u 944, now I can buy 115u 944B but I not sure is could be work.  The label from the sides is the same 6ES5 944-7UB21 but in the front one have no B and the other one have B.

Other question, Can I change de CPU and read the program from the eprom or I need to do something else like a do something with computer? Because I don't have any cables and any programs.

I hope you can help me or give me any suggestions.

Thank you!

Hello edwinrg69,

in my opinion you ca change the 944 to 944B without any problems.
The 944B is faster and the "second generation" of the 944.

Normally should be the complete programm at the EPROM.
You can change the CPU and you plug in the EPROM an it should works.

One important thing is if there is a opertion panel to change some values at the DB.. Then you must save this values and after the start of the new CPU you must also adjust the values.

I hope this help you a little bit.

regards
CaOd

CaOd thanks for you help, 

Yes we have operation panel, the values that you talking are changeable in the same operation panel?

Another doubt is, when I trying to do the overall reset one of the time I forgot to pull the eprom, it is possible that eprom were erase? 

Thank you in advance 

edwinrg69

CaOd thanks for you help, 

Yes we have operation panel, the values that you talking are changeable in the same operation panel?

Another doubt is, when I trying to do the overall reset one of the time I forgot to pull the eprom, it is possible that eprom were erase? 

Thank you in advance 

Hello edwinrg69

An overall reset will not damage the EPROM

When you insert the 944B you should carry out a reset with out the EPROM fist.

The run off power, insert the EPROM and turn the power on again.

Reagrds / m.f.g

 Sorry for my straight message--EPROM has more than 30 years history , not only used by Siemens but also a lot of control from other companies. EPROM is very safety data storage, it is very hard to erase. only Ultraviolet radiation (light) can erase it and the small windows on the chip should be open               So No worry about data lost.

edwinrg69

CaOd thanks for you help, 

Yes we have operation panel, the values that you talking are changeable in the same operation panel?

Another doubt is, when I trying to do the overall reset one of the time I forgot to pull the eprom, it is possible that eprom were erase? 

Thank you in advance 

Hello edwinrg69,

of course can you use the 843B.

You should pay attention for 2 things:

• the 943 B is not so fast like the 944B, the operation time per command (bit, load, compare...9 are the same
• the 943B have not so enough working memory (RAM) and the maximum program-code at the EPROM ist not so much like the 944B

If I remember right ist the improvment of the series S5-94x to S5-94XB so big that you can use the 943B as replacemant.

I hope this is helpful again

regards
CaOd

I tried to install CPU 115 943B in my PLC who have 944 before, but when I tried to load the program from the eprom the stop light just flash and do not stop flashing.

What could be happen? 

Thanks in advance 

6ES5 375-1LA71? This EPROM can only use in CPU944.