1747-CP3 and serial cables

I cannot connect mu 1747-L532 processor to PC using regular serial cable DB9 f/f. I'm interesting the difference between 1747-CP3 cable and regular serial cable.

Normally 2-3, 3-2, 5-5 cable will work.
Correct pinouts for CP3:
2 - 3
3 - 2
4 - 6,1
5 - 5
6,1- 4
7 - 8
8 - 7

Problem possible in Channel 0 configuration inside PLC, it may not be set for DF1.

By "regular serial cable" you probably mean a "straight through" cable where each pin connects to the same pin on the other side. That won't work between a PC and a SLC-5/03.

Because the SLC-5/03 serial port is a "DTE" type port, just like the one on your computer, you need to swap the transmit and receive pins. That's what's done inside the 1747-CP3 cable, as well as some handshaking jumpers that Contr_Conn pointed out.