I want to connect my DIY basic stamp via RS232 MAX232 to the serial port on my laptop. Now since I'm a complete newbie in electronics, what do I do with Ground Pin 5 on the DB9? I assume ground means I have to connect it to some insulator with 0V? Maybe you can also explain why there has to be a GND pin anyway, what is the purpose?
Electronic – Where to connect DB9 Ground Pin on a Serial RS232 connection
basic-stampbreadboardgroundrs232serial
Related Solutions
It will depend of the software that you're using.
A) In my case, as I develop my own PC software, I've never used other pins, only RxD, TxD and GND. So, in this case you can left other pins open. This is called as null modem without handshaking
B) Yes (assuming GND is being considered)
C) Again, it will depend of the software on PC side. Some softwares you can configure to not take care of hardware control. Others will require RTS/CTS handshaking, so you can do a null modem with loop back handshaking
Source of the pictures: RS232 serial null modem cable wiring
The problem was an undocumented even parity bit required by the device I need to control (a Bentel Kyo300 alarm security panel), but even if I found which the problem was a limitation in the serial wireless modules prevents to re-generate the parity bit on the destination end-point.
Those serial-wireless adapters have, in fact, fixed serial-side configuration of 8N1... I solved buying better and configurable serial wireless modules (APC220) :)
I've learned a lot about hardware-level serial communication during this discussion so I'm happy even if I spent few more euros ;)
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Best Answer
I don't know the STAMP controllers but in this context 0V = GND. All voltages are relative to some reference point. In this case it is 0V on one device and GND on the other device. They just have different names for the same reference point.
If you start going in to mains electrical then 0V may not be GND as this could be Safety Ground (referred to as GND often ) and 0V could be isolated so be careful.