i want pull a data cable and instrument cable in a conduit please any one suggest me can i pull the cable or need some gape between serial signal and analog signal
As long as the RS-422 cable is twisted pair, I don't see any chance of interference between cables. The RS-422 line is terminated with a resistor of the same impedance as the twisted pair wires, further insuring the wires don't act like an antenna. I have used RS-422 over a mile without noise pick up in standard telephone cable. Do pay attention to isolating the 422 receiver IC from ground, because inside the IC there are paths to local ground. If there is a difference of over a few volts between the driver ground and receiver ground, one of the the ICs will blow up. The distance has nothing to do with the ground potential differences.
Usually at least one of the cable types used in such a case is a shielded coax, although I've seen it done on the cheap with twisted-pair too. One significant factor is the frequency rate on the data cable. Ferrite loops on the cables is a typical trick to prevent noise bleed-over too. If you want a really good answer try calling the support line for a company called Black Box.
