Functions.md

Serial Port VBA Functions - Minimal Set

All functions support one pre-defined Com Port number with existing pre-configured settings only

VBA Function	Returns	Description
start_com_port	Boolean 1	Starts com port with existing settings
read_com_port	String	Returns all 2 waiting characters from com port
read_com_port(6)	String	Returns up to 2 specified number (6) of waiting characters from com port
send_com_port($B$5)	Boolean 1	Sends 3 contents of Cell $B$5 to com port (Excel Worksheet Only)
send_com_port("QWERTY")	Boolean 1	Sends 4 supplied character string to com port
send_com_port(COMMANDS)	Boolean 1	Sends 4 character string defined in VBA constant or variable COMMANDS to com port
stop_com_port	Boolean 1	Stops com port and returns its control back to Windows

Com Port number defined in declarations section at start of module

Private Const COM_PORT_NUMBER as Long = 1

Footnotes

1. Function returns True if successful, otherwise False ↩ ↩² ↩³ ↩⁴ ↩⁵

2. Maximum characters returned = read buffer length (fixed value)
   More waiting characters beyond read buffer length may remain unread until next read_com_port call. ↩ ↩²

3. Excel will re-send if cell $B$5 contents change. ↩

4. Function will block until all characters are sent or write total constant timer expires.
   Maximum characters sent limited by timer Write_Total_Timeout_Constant value. ↩ ↩²