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Topic: (RESOLVED) Serial commands from Uno using DB9 shield to DB25 (Read 632 times) previous topic - next topic

Riva

You don't  have the voltage level needed for that it's rs232c that's needs a 6 volt or higher swing you only have a 0 to 5 volt with this RS232 Shield For Arduino
you need a max 232 chip ±30-V Input Levels
It looks like the shield has a MAX232 chip and the MAX232 chip can generate the required RS232 voltages from 5V with its charge pump and external capacitors.
Don't PM me for help as I will ignore it.

be80be

The data sheet for that does not state that all that have a real max 232 chip clearly state they are in spec
That shield clearly states it 0 to 5 volt that will not work on anything that is truly rs232c

Riva

The data sheet for that does not state that all that have a real max 232 chip clearly state they are in spec

That shield clearly states it 0 to 5 volt that will not work on anything that is truly rs232c
Sorry but I'm not understanding your first sentence very well. Are you referring to the datasheet for the MAX3232 chip used on the shield or some other datasheet?

The shield will only be supplied with 3.3V or 5V from an Arduino but the MAX3232 chip on the shield uses capacitors to pump the supply voltage up to the levels required for RS232.
Don't PM me for help as I will ignore it.

be80be

First off I know how a max232 works the problem here is the datasheet for the shield being used doe not state its a max 232 it
said it only does  5 volts

Now and shield with a real max232 will brag about it and state it is fully able serial port.

I bet the posters is not giving the needed voltage levels.

Paul_KD7HB

First off I know how a max232 works the problem here is the datasheet for the shield being used doe not state its a max 232 it
said it only does  5 volts

Now and shield with a real max232 will brag about it and state it is fully able serial port.

I bet the posters is not giving the needed voltage levels.
One of the picture shows an overhead view with an IC showing the MAX3232 identification. So the it will produce 8+- volts.

Paul

be80be

Id check it my bet is still it's not doing it right 

krooney

Hey everyone,

Problem solved!!!! The gender changer was the issue. I was using a male to male DB9 gender changer because both my serial cable and the shield have female DB9s. Pretty sure that this effectively wired Tx to Tx and Rx to Rx instead of Tx to Rx both ways.

I've manually wired the shieldTx to cableRx, shieldRx to cableTx, and GNDs and now the communication works beautifully, with the very simple code of Serial.println("command");

Can't thank you guys enough for all your help. So very appreciative for all the ideas. Sorry to have everyone brainstorming ideas when it was really a very silly wiring error on my end.

Paul_KD7HB

Gosh! I bet you are the first one that ever happened to! Good luck and come back again, sometime.

Paul

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