To keep the HMI informed of digital changes a RDC command can be submitted. When a digital input or output changes, a RDC data message is send to HMI. 

RDC Send@RDC,<1|0>,<tagname>,<mask|auto>Mask or Auto is depending of the I/O type. Resp Input|Output
Possible error messages coming from the board
%FAT-UNKCMD-BTSERIAL, Unknown command received
%RDC-UNKCMD-BTSERIAL, Unknown tagname received