Multi-channel Serial Port

The EM1202EV has four serial ports internally. The EM1202EV-RS has an RS232 port with DB9M connector, while "-TM" and "-TS" devices have TTL serial port available through a TTL interface connector, which is a standard pin header with 2mm pitch.

The EM1202EV implements three outputs, four inputs, and one "spare" input (CD). Each of the three outputs can be used as a TX line of a serial channel, or as a control output such as RTS or DTR. Input lines can be used as an RX line of a serial channel, or as a control input such as CTS or DSR. The spare input cannot work as an RX line. This input is not used by the serial-over-IP application supplied by Tibbo and will be largely omitted from further discussion. Your Tibbo BASIC/C application can always use this extra input if you require it.

With three outputs and four inputs, the EM1202EV can be said to offer 3.5 serial "channels". We say "3.5 channels" and not "four channels" because one channel will only have RX line and no TX line (remember, there are four inputs but only three outputs).

DB9M connector pin assignment:

*Not used in Tibbo serial-over-IP application. Your Tibbo BASIC/C program can use this line if needed.

TTL interface connector pin assignment:

*Not used in Tibbo serial-over-IP application. Your Tibbo BASIC/C program can use this line if needed.

Serial-over-IP application offered by Tibbo defines 15 "mapping options", or ways in which available I/O lines are utilized ("spare" input is not used or shown). These are presented in the table below:

"Available signals" column shows a particular combination of I/O lines for each option. For example, option 0 defines the standard serial port arrangement with RX, TX, CTS, RTS, DSR, and DTR lines. Option 2 gives you one channel with RX, TX, CTS, and RTS lines, one more channel with just RX and TX lines, and yet another channel with a single RX line. The TX line is "missing" because, once again, there are only three outputs available. This is why this line is shown in grey lowercase (tx).