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RS-232 Communication troubles with receiveing data

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Hello all,

I using a Samba 3.5 to send and receive data to/from a weight indicator.

I only have (for now) 1 com port on the samba so I cant use the online test while connect to the indicator, so I used a terminal on my PC to "replace" the indicator when connected to the samba and "replace" the samba when connected to the indicator. The indicator has 2 comm modes - response to a "W", or send the weight automatically ~5 times a sec.

When Im using the terminal to talk to the samba/indicator everything works great - the samba sends "W" and it's received on the terminal, and when I reply with "+XXX.XXX" the samba receives it (shows on the monitor in the info mode) and displays it in the HMI like I programmed. 

When I connect the indicator to the PC I can send "W" and receive "+XXX.XXX" as expected.

All this is great and all, but somehow when the indicator is connected to the samba nothing is received (on the samba end). even in the info mode monitor nothing is showed in the Rx box. Not in respose to "W" and even in the auto send mode where it sends the weight without any command.

Now, as I understand (could be wrong), no matter how I program the samba, when it receives data through the com port it shows on the serial monitor, right?

so how can it be that nothing is received?





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6 minutes ago, kratmel said:

I think - you have standard problem with TX RX wires crossed on cable.

Samba standard wire is crossed for PC connection. Weight sender is crossed for PC connection. 

And Samba to Weight is not crossed...


Ok thats a good idea.. any easy way to check/solve? 


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Just now, kratmel said:

Please  post weight device manual to topic.

TX RX pin in DB9 connector pin 2 and 3 must be checked.

Samba TX must go to RX pin weight device and Samba RX must be connected to weight device TX.


I "modified" the cable I use and it worked! thanks so much kratmel 

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