COMSTAT

Format

number1 = COMSTAT (number2)

Description

This statement returns the status of a com port. Number2 should contain "0" for COM1, or "1" for COM2. The status of that COM port is returned in number1. Each bit in number1 represents a different piece of information. These are described in the table below. Note that you may test if a bit is on/off using the ZBIT command.

Example

PORTSTAT = COMSTAT (0)
DATAREADY = ZBIT(8,PORTSTAT)
IF DATAREADY = 1 THEN GORECEIVE:
These statements do the following. The first retrieves the status of COM1 to the variable PORTSTAT. The second checks to see if bit 8 is on, DATAREADY will contain 1 if so, otherwise it will contain 0. Since Bit 8 is used to determine if data is waiting to be received from the port, if DATAREADY = 1 then the program will transfer to the label GORECEIVE: which would contain code to RECEIVE data from the port.

Comments

Status Codes Returned by COMSTAT (Meaning when set to 1)
 
0 Delta clear-to-send
1 Delta data-set-ready
2 Trailing-edge ring detector
3 Delta receive line signal detect
4 Clear-to-send
5 Data-set-ready
6 Ring Indicator
7 Received line signal detect
8 Data Ready
9 Overrun error
10 Parity error
11 Framing error
12 Break-detect error
13 Transfer holding register empty
14 Transfer shift-register empty
15 Time-out error

See Also

  • OPENCOM
  • SEND
  • RECEIVE