M
I have very big problem with Simatic controllers (CPU 316-2DP), exactly with communication between controllers and operating stations. Configuration of my system is: two controllers, and two operating station (WinCC 5.0) communicate each other by Profibus S7 (1.5 Mbit/s). Computers is equipped with communication cards CP5613. Distance between first and last component of the network is about 15 meters. Everything would be great, but the communication between PLC and OS is disconnected. It is happen irregularly, sometimes every 15 minutes, sometimes 5 times per minute. Sign of this effect is visible on the screen of the OS: all of the analog variables is dissapeared for 1-2 seconds. During this effect I has observed error number 8304 in Channel Diagnotic (software which is include with WinCC). Unfortunately I haven’t found description of this error in documentation of WinCC. Additionally I have observed that “Cycle Overflow” is incremential after disconnection. Amount of the variables which are read from controllers is about 900.
I have created very similar network in laboratory, but I have used CPU 315-2DP. In this case, everything is great – communication is not disconnected even once per week.
I have spoken to someone from Siemens, but they don’t know why communication is disconnected so often. They told me, that I should try to use acyclic read variables from PLC. It really helped it, but now refresh the variables from PLC is very, very slow (about 10-12 seconds). It is unacceptable. I have interested why the communication with CPU 315-2DP is great, and with CPU 316-2DP is not.
Is anybody who can help me???
Regards
MI
I have created very similar network in laboratory, but I have used CPU 315-2DP. In this case, everything is great – communication is not disconnected even once per week.
I have spoken to someone from Siemens, but they don’t know why communication is disconnected so often. They told me, that I should try to use acyclic read variables from PLC. It really helped it, but now refresh the variables from PLC is very, very slow (about 10-12 seconds). It is unacceptable. I have interested why the communication with CPU 315-2DP is great, and with CPU 316-2DP is not.
Is anybody who can help me???
Regards
MI