Shamyl

I'm using 1756-L55 ControlLogix5555 Controller with 2xDI, 2xDO, 1xAI, 1xAO, 3xRTD and 1x1756-ENBT/A for Ethernet communication. Now the problem that I'm facing is that sometimes the PLC just crashes. All the I/O modules are displaying Fault indications, and communication just cannot be established, either through Ethernet or through RS232. As such any fault cannot be read from the controller's memory. Also, the fault cannot be cleared from the controller keyswitch. It is cleared only once the controller is given a power cycle (switched off and on). The fault is removed but the memory is all washed out alongwith the Fault Log. Once the software is downloaded the controller starts working again fine. Kindly suggest what the problem might be; we cannot afford many such crashes as the controller is installed on a critical system

Hi, I'm using FR-A500 inverters communicating with Citect V5.40 (HMI)and Melsec A1SJH (PLC) via RS-485. The HMI is for enabling the inverters and giving them speed reference, apart from monitoring the loading currents of the inverters. Now the problem is, some of the inverters are only taking commands from the HMI (speed reference and 'on/off' command) but the 'on/off' status and currents are not being displayed. While the communication with the other inverters are perfectly fine. I tried finding parameters related to what data should be sent over the communication cable (like there are in Siemens MicroMaster), but found none. What could be wrong? Regards, Shamyl