Serial Port VBA Functions - simplified set

VBA Function	Returns	Description
`start_com_port`	`Boolean` ¹	Starts com port with existing settings
`start_com_port("baud=1200")`	`Boolean` ¹	Starts com port with supplied settings ² in string
`start_com_port(SCANNER)`	`Boolean` ¹	Starts com port with settings ² defined in VBA constant or variable SCANNER
`check_com_port`	`Long`	Returns number of read characters waiting. -1 indicates error
`get_com_port`	`String`	Returns a single waiting character string from com port
`read_com_port`	`String` ³	Returns waiting character string from com port
`put_com_port("A")`	`Boolean` ¹	Send a single character string to com port
`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
`send_com_port($B$5)`	`Boolean` ¹	Sends ⁵ contents of Cell $B$5 to com port (Excel Worksheet Only)
`device_ready`	`Boolean`	Returns `True` if port started and Data Set Ready (DSR) input signal active
`stop_com_port`	`Boolean` ¹	Stops com port and returns its control back to Windows

Private Const COM_PORT_NUMBER as Long = 1

Footnotes

Function returns True if successful, otherwise False ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸
Port settings if supplied should have the same structure as the equivalent command-line Mode arguments for a COM Port ↩ ↩²
Maximum characters returned = read buffer length (fixed value)
More waiting characters beyond buffer length may remain unread.
Use check_com_port to confirm any remaining character count if required. ↩
Function will block until all characters are sent or write timer expires.
Maximum characters sent limited by timer Write_Total_Timeout_Constant value. ↩ ↩²
Excel will re-send if Cell $B$5 value changes ↩