Memory Bottleneck

[Mach390]

Hello Siemens Guys I usually program Allen Bradley, but our new plant has put in Siemens. I will make changes to the program, but after a while I get a "Possible load memory bottleneck" warning. I tried to copy the ram to the rom, but I get another warning that says it is not possible with the current module. We have a CPU 416-2. Thanks for any help! Edited March 12, 2008 by Mach390

[Rod_Hackney]

I would check available memory on the processor as compared to the program additons you are adding. Also, check revision of S7-400 you are using, you may have a problem that a firmware upgrade could fix. A call to Siemens should get you an answer. Siemens will usually get back to you in a few hours even if you do not have a current service contract.

[Mach390]

What I found out to relive this problem was to do an upload, then download to the memory card. When I did this however, I did not correctly do an upload so after I downloaded to the memory card a lot of tags that displayed information on the HMI reverted back to older values or information. Doing the upload correctly should prevent this from happening though. This however requires the PLC to go into the stop possition, and I do not get a chance to do this very often. So I bought a 2MB RAM card to replace the 1MB FLASH card that was in the PLC. This allows many more downloads with out doing anything that would put the PLC into the STOP position. Once we are done making changes to the plant, I will put the EPROM card back in, and download a current version of the program to it. Edited April 8, 2008 by Mach390

[jacekd]

Next time try to compress memory first. See Step7 online help.

[Mach390]

I had been compressing the memory, but the CPU still has to be in STOP mode to do that. After a while of compressing, my memory was still at 85% or so, and this would only allow me to do a couple of downloads before I ran into the memory bottleneck.