Arduino RS485 shield TXD led always on

I'm running the Arduino RS485 shield attached to an Arduino UNO Wifi. The test code appears to work correctly, turning the red LED on and off with “V” sent from the serial monitor. But the TXD light remains on constantly.  Is that normal?  Also, the test code downloads to the shield successfully whether the run/program mode switch is in the On or Off position. Is this shield functioning as expected?