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====== RS-232C HOWTO ======

A PC's RS-232 interface typically use +/-12V signals, while the CUBLOC's RS-
232 interface uses 5V signals. To avoid the need to make a separate circuit
to convert the +/-12V signals from the PC to the 5V signals of the CUBLOC,
and vise-versa, the CUBLOC was built with both a +/-12V RS-232 interface
(channel 0 – the download port) and a 5V RS-232 interface (channel 1).

The +/-12V RS-232 interface (channel 0) is provided on pins 1 and 2. For
the CB220/320 a 5V RS-232 interface id provided on pins 10 and 11.

{{ :cubloc:rs232c_howto:cb220rs232_1.png?nolink |}}

For the CB280/380, RS-232 channel 1 can make use of either 5V or +/-12V
signals, but the pins are different. For a 5V interface, use pins 49 and 50.
For a +/12V interface use pins 33 and 34.

{{ :cubloc:rs232c_howto:cb280rs232c.png?nolink |}}

Downloading programs to the CUBLOC is very easy, since the PC's RS-232
interface can connect directly to pins 1 and 2 of the CUBLOC. For RS-422
and RS-485, 5V signals are provided on RS-232 channel 1.

For the CB280, a +/-12V RS-232 interface is provided in addition to the 5V
interface, but only one can be used at a time.
The following shows a simple circuit diagram to convert a 12V RS-232
interface to a 5V RS-232 interface using a MAX232 chip.

{{ :cubloc:rs232c_howto:rs232circuit.png?nolink |}}

NOTE: For capacitor values, please prefer those recommended in your MAX232 IC's datasheet.

The MAX232 is a very useful chip for converting between 5V and +/-12V
RS-232 signals.

{{ :cubloc:rs232c_howto:max232.png?nolink |}}

For the CB400, CB405, and CB405RT, see [[cubloc:using_rs-232_on_the_cb400_405_405rt|Using RS-232 on the CB400/405/405RT]]

[[cubloc:index|CUBLOC - Embedded Controller]]