Guru
Joined: 05/03/2018
Location: NetherlandsPosts: 5994
| Posted: 09:10am 06 Jan 2025 |
Hi Mark,
When I cannot use INPUT for keyboard, I use something based on below:
'this replaces INPUT txt$ and has a time-out
Sub get_txt_timeout
Local a$,b$,t
b$="" : t=Timer 'timer start
Do
a$=Inkey$
If a$<>"" Then b$=b$+a$:t=Timer:Print a$;
Loop Until a$=Chr$(13) Or (Timer-t>5000) Or a$=Chr$(10)
If a$=Chr$(13) Or a$=Chr$(10) Then
txt$=b$
new_cmd=1
Else
new_cmd=0
End If
End Sub
Sub get_txt_timeout
Local a$,b$,t
b$="" : t=Timer 'timer start
Do
a$=Inkey$
If a$<>"" Then b$=b$+a$:t=Timer:Print a$;
Loop Until a$=Chr$(13) Or (Timer-t>5000) Or a$=Chr$(10)
If a$=Chr$(13) Or a$=Chr$(10) Then
txt$=b$
new_cmd=1
Else
new_cmd=0
End If
End Sub
You can also add delete (control-H) detection and trim off the leftmost character from b$. Above routine (on terminal screen) seems to delete with control-H, but it only adds a control-H to the b$ string, in stead of removing a character from it.
This has a timeout, and checks if the strin is terminated correctly. The esssence you need is the DO-LOOP.
For serial port I read character for character until I hit a delimiter (i.e. <CR>).
-or- below code is similar and adds a (some) character(s) to a string in a loop, and when for a defined period nothing is received (string length not changed), it returns. This works fine for MODBUS where messages are sent in compact strings without any dead time between characters (actually a dead time is defined as a message separator).
'modbus defines
looptime=50 'ms
timeout=1000 'ms
loops=timeout/looptime 'number of loops in 1000ms
'waiting for a response
old_a = 0 : success = 0
For i= 1 To loops '20x50ms = 1 sec
Pause looptime 'minimum time for a message to get in
If Loc(1) Then e$=e$+Input$(Loc(1),#1) 'get answer
'check if we have data, and no new data came in for 50ms (loop time)
If old_a > 0 And Len(e$) = old_a Then success = 1 : Exit For
old_a=Len(e$)
Next
looptime=50 'ms
timeout=1000 'ms
loops=timeout/looptime 'number of loops in 1000ms
'waiting for a response
old_a = 0 : success = 0
For i= 1 To loops '20x50ms = 1 sec
Pause looptime 'minimum time for a message to get in
If Loc(1) Then e$=e$+Input$(Loc(1),#1) 'get answer
'check if we have data, and no new data came in for 50ms (loop time)
If old_a > 0 And Len(e$) = old_a Then success = 1 : Exit For
old_a=Len(e$)
Next
Volhout
Edited 2025-01-06 21:23 by Volhout