I used two CompactLogix Controllers (1769-L35E) for my project. They communicated back and forth through message routine. Lately, customer complained that they lost control on some machines. When I tried to get online with one of the controller, RSLink could not connect to it (error 701-80042535) even thought I could ping it. Naturally, I suspected that it maxed out on connections (L35E maxes out at 32 connections). However, when I checked on its web page, there were only 16 connections used. It was strange.
After struggled for hours, I checked the controller with Task Monitor. Task Monitor showed98% of memory was used. That’s not good.
After I shut down a PC which also talked to the L35E, I was able to get online. Here was the memory usage of the controller. It showed only 15,412 bytes available memory (>1% available memory)
I knew that memory usage was much lower when I downloaded the code. There must be some memory leaks in the controller. So I cycled power to the controller. When the controller powered back up, it showed there was 183,676 bytes available memory (11.6% available memory).
From this point on, all controllers and PC talked to the L35E without problem.