Knowledge Base

There are 2 x TTL level serial ports and 1 x RS485 port on the HMI430/700.  The HMI700 also has a RS232 port that is shared with one of the TTL ports.

The RS485 port may be used for normal serial communications (MODBUS or user defined communications) or switched to Xwire to allow distributed I/O schemes.

Serial port numbers are as follows:

COMHMI   EQU   251  ;a virtual serial port that is the SimpleHMI interface to the touch screen
COM0 EQU 252 ;the TTL serial port
COM232 EQU 252 ;HMI700: real 232 port, shared with COM0
COM1 EQU 253 ;the TTL serial port
COM485 EQU 254 ;the RS485 port (may be used as Xwire via the XwirePhys 1 instruction)
COMUSB EQU 255 ;the USB serial port (used by SPLat/PC, but may be changed to user coms 10 seconds after your app starts)

A ready to use list of all HMI430 I/O assignments is available here:

For specific information about these ports, please see the relevant pages below.