EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Keex on September 29, 2017, 07:40:17 am
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Hi,
I am currently building an application that interfaces two RS232 devices with an Arduino using the hardware serial ports and in my prototype I am currently using two individual TTL->RS232 converters. I need both to send to and receive from both of the devices.
I now want to build my own version of the converters using a MAX232 chip, but I am getting a bit confused by the specifications. The package has two RX/TX lines, so on first glance it seems to me that I need only one of these chips to work with the two devices independently. However, spec lists of the chip say the following:
Number of line drivers 1
Number of Receivers per Line 1
I am not experienced with the lingo involved, so this sounds to me that I can only use one device at a time. I can't find a clear statement anywhere if the two RX/TX channels of the MAX232 can be used completely independently from another.
So to summarize the question: Can I use just one MAX232 to talk to two independent RS232 devices without interference or do I need two of the chips?
Thank you.
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I don't know where you found that information, but the datasheet (http://www.ti.com/lit/ds/symlink/max232.pdf) clearly states that you have "Two Drivers and Two Receivers".
No problems in using those for separate RS232 channels (I did)!
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Old style RS232 used extra handshake lines too. So they needed a second driver and receiver for a single RS232. However the extra Handshake lines are not always used. So the max232 is good for one channel with HW handshake or 2 channels with only rx/tx.
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Perfect. That is the information I needed. Good to hear that you have used it yourself @newbrain, and thank you for the additional explanation @Kleinstein. :-+