Panagiwtis Posted October 9, 2014 Report Share Posted October 9, 2014 I have a serious problem with V200-18-E2B (connected to a V570) that controls the inverter (GRUNDFOS CUE) of a pump via an analog output (0-10V). We are talking about a cooling system and I am using PID in order to control this analog output. The process value is a temperature sensor and the control value is the MI that controls the analog output (after Linearization) that goes to the inverter. When the PID is not active I use a strore direct function that stores the number 300 (30%) in the MI. The problem is that sometimes while the system seems to function normally, the HMI correctly shows that the inverter is working at 100% and I can see in the visilogic that the current value of the output MI is 1000 (100%) and 4095 in the real output (out of linearization block). However, in reality the inverter is working on its minimum safety setting (from its manufacturer) of 25% and when I measure the analog output of PLC with a voltmeter, the reading is 0V!!! I can't figure out why this happens, this problem drives me crazy and its a disaster for the customer...... Please, I need some help to find a way out of this..... PS1: I am not 100% sure but I think (i am many kilometers away from the plant at the moment) that this happens only when the system has made a complete cycle, the user has made a shut down to the system and restart it after this first shut down. PS2: The inverter sits inside the electric control panel and it's near the plc. Could this create a problem like this, or I can exclude that because of the fact that the problem doesn't occur all the time? Quote Link to comment Share on other sites More sharing options...
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