====== Using RS-232 on the CB400/405/405RT ======

The CB400, CB405, and CB405RT modules have 3 serial ports exposed as 5V TTL UARTs.

^  Channel  ^  CUBLOC Port  ^  Signal  ^
|  1         | P42           | RX       |
|  :::        | P43           | TX       |
^           ^               ^          ^
|  2         | P8            | RX       |
|  :::        | P9            | TX       |
^           ^               ^          ^
|  3         | P56           | RX       |
|   :::         | P57           | TX       |

The CB400/405/405RT modules also have a built-in [[https://en.wikipedia.org/wiki/MAX232|MAX232]] level converter to convert the 5V TTL UART signals to +/-12V RS-232 signals.  To utilize the level converter, connect a serial port's RX and TX pins to the TTLRXE and TTLTXE pins respectively, and then the RS-232 level signals for those pins will be available on the RXE and TXE pins.

The following image illustrates how to expose serial port 3 as RS-232.

{{ :cubloc:channel3_rs232.png?800 }}