FP2 Serial Data UnitOperation If an Error Occurs6 − 46.1 Operation If an Error Occurs6.1.2 When the Serial Data Unit ERROR LED LightsWhat the ERROR LED doesThe ERROR LED on the serial data unit lights there is a problem with communicationbetween the unit and the external device. There are two ERROR LEDs, [ERR1] and[ERR2], for each channel.SDUSDUSD RD ERR SD RD ERR ALARMCOM.1 COM.2ERROR LEDSerial data unit operation when the ERROR LED lightsOperation of the unit continues even if the ERROR LED lights.If an error occurs during reception, the frame currently being received is cleared, and theERROR LED lights. If the next frame is received normally, however, that frame isprocessed as a received frame, and the ERROR LED goes out.CPU unit operation when the ERROR LED lightsOperation of the CPU unit is not affected.The contents of the error which occurred can be read as I/O contact information, usingthe CPU unit.For an example of a retry program, refer to section 8.1.2.
