S
The PLC is very slow in processing the analog signal (4-20mA) which takes about 3 minutes to respond to the signal. The signal is a feedback from a modulating motor unit. Field tests were done and the modulator was generating a feedback between 4 to 22mA. The modulator feedback was removed and current source simulator was used to inject the 4-20mA signal, but the same delay the input data processing was experienced. The PLC was removed from the cabinet and tested on the workbench by simulating a 4-20 mA signal from a current simulator and the same problem still exist. The analog input card module was removed after power down to do a visual check for any damage but no visible defects were identified. When the module was slotted back into the PLC and powered up, the 4-20mA signal was not registered as raw count in the PLC. The configuration is OK to read 4-20mA signal. The PLC uses PL7 Pro V4.5 software