If anyone is struggling to configure a Dragino RS485 device to talk Modbus to a slave, note that AT+COMMANDx and AT+CFGDEV require spaces between the bytes.

Format it this way: AT+COMMAND1=01 03 00 05 00 01,1

Not this way: AT+COMMAND1=010300050001,1

Before I added the spaces, AT+COMMAND1=? would not return the same result input.

I also wish to thank Gardener Granny for her post on using a similar Dragino device with a soil moisture sensor.