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Writing to a Serial Port

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# 15  
Old 10-19-2014
The reason why the serial port is hanging is beacuse of two things, either:-

1) The serial speed is greater than 9600bps and requires HW control.
2) IF the port is reading a decimal value of 0, (zero), then nothing __seems__ to happen.

Another reason could be that the remote nachine is not on the same speed as the local one, but highly unlikely.

Have you tried testing your local machine first with a loopback plug at the speed you require?

Get that side working first then hook up to the remote machine and work on getting them both talking.
# 16  
Old 10-19-2014
Thanks wisecracker -

I think I set the port speed to 9600.

From minicom
Code:
-----------------------------------------------------------------------+                                  
Comp| A -    Serial Device      : /dev/ttyS0                                |                                  
Port| B - Lockfile Location     : /var/lock                                 |                                  
    | C -   Callin Program      :                                           |                                  
Pres| D -  Callout Program      :                                           |                                  
    | E -    Bps/Par/Bits       : 9600 7E1                                  |                                  
    | F - Hardware Flow Control : Yes                                       |                                  
    | G - Software Flow Control : No                                        |                                  
    |                                                                       |                                  
    |    Change which setting?                                              |                                  
    +-----------------------------------------------------------------------+

I'm a newbie. I've ordered a loopback plug from Newegg.
How do I use it?
# 17  
Old 10-19-2014
So have you been successful with communicating with this device within minicom? That'd be the first step before trying to with PHP.
# 18  
Old 10-19-2014
Thanks neutronscott -

Next step, please.
# 19  
Old 10-19-2014
Is that a yes?

I looked at some weight protocols and you may need to send \r:

Code:
$ printf '\rW\n' >/dev/ttyS0
$ cat /dev/ttyS0

You should see a weight then. If so, and your permissions are correct, your PHP may work using \rW\n
# 20  
Old 10-20-2014
Thanks neutronscott -
Code:
cat /dev/ttyS0

No output
# 21  
Old 10-20-2014
Can you please confirm that this has worked in minicom?

Another guess is that the serial port cannot be opened & closed. We can keep it open and attached to another fd.

Code:
exec 3<>/dev/ttyS0
printf '\rW\n' >&3
cat <&3
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