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How can I replace cpu 115U 942B with 115U 942 ?

Created by: suhato87 at: 12/3/2010 12:50 PM (7 Replies)

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12/3/2010 12:50 PM	Rate (0)
suhato87 Posts: 5 Rating: (0)	Dear expert, Currently I have a cpu 115U 942B running in the machine and a cpu 115U 942 in the store Can I replace cpu 942B with cpu 942? If it is posible, how can I do that? I use Step5 version 6.6 if I upload program from cpu 942B and download that program to cpu 942, will cpu 942 run smoothly or not ? Best regards
suhato87 Posts: 5 Rating: (0)
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12/4/2010 9:50 PM	Rate (0)
jklm Platinum Member Joined: 12/22/2006 Last visit: 1/25/2022 Posts: 1742 Rating: (303)	Hello, I found this entry: http://support.automation.siemens.com/WW/view/en/4161605
	Best regards jklm Suggestion was helpful? Feel free to rate it.
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12/5/2010 4:53 PM	Rate (0)
suhato87 Posts: 5 Rating: (0)	Hi, Thank for your imformation. I just really want to know that if I can replace cpu unit 942B with 942 unit. It is very important. Can anyone help me? Thanks.
suhato87 Posts: 5 Rating: (0)
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12/5/2010 5:50 PM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 2/16/2023 Posts: 2705 Rating: (311)	Hi, the CPU 942A is an older CPU for the S5-115U. For the CPU 942B DB1 is made with COM DB, this DB1 may not work in a CPU 942A. Further there are so far I know not so much differences, the A is only less performant (divided by two I believe).
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
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12/9/2010 7:40 AM	Rate (0)
Simaticus Bronze Member Joined: 1/30/2007 Last visit: 6/3/2022 Posts: 262 Rating: (24)	Dear suhato87, regarding your enquiry you ought to know that a cpu942(A) is very slow as soon as a lot of data blocks is used in your plc program (factor about 60). If no data blocks are used cpu942 should do ok. For comparison the cpu942B is about as fast as a cpu943A. Good luck
	Last edited by: Simaticus at: 12/9/2010 7:41 AM
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12/9/2010 8:17 AM	Rate (0)
KayBee Posts: 241 Rating: (7)	For this Late is right. I may also sugest the same as 942B is newr has DB-COM option,
KayBee Posts: 241 Rating: (7)
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1/6/2011 5:14 PM	Rate (0)
suhato87 Posts: 5 Rating: (0)	First of all, I want to say thank to all of you for replying me. Talking about my problem, in my factory, There are two machines of the same type but using two types of S5 plc ( 115U 942 and 115U 942B). Recently, the plc 115U 942B have some problems and it will probaly be broken down ( I guess ). we have a cpu 115U 942 for spare. The main point is this, I have tried to replace 942 ( spare) for 942B ( in the machine) by uploading program from 942B cpu and downloading to 942 but it dont work. Because these CPUs are used in the same type of machine so I think they can be replace. To tell the truth, I dont have much knowledge and experience of S5 plc. Can anyone help me to show the way I can do it. I use step5 V6.6. Thanks and best regards
suhato87 Posts: 5 Rating: (0)
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1/13/2011 2:10 PM	Rate (0)
oem Posts: 14 Rating: (3)	Good day I had a similar problem, years ago. Old CPU's do not have too much "on board" memory and need external support from EPROM memory cartridge. I saved some blocks on EPROM module and the rest I left it in the program transferred to the PLC. The procedure was: PLC OFF>remove the battery>insert EPROM>PLC ON - STOP mode>transfer the rest of program> PLC RUN>insert the battery. In my case, it was a memory bottleneck due to different version of the CPU. It maybe helps you.
oem Posts: 14 Rating: (3)
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