ML-1400 PLC and arduino

hello friends
i am trying to connect my plc ml-1400 with arduino serially

i want to know that do i need rs232 ttl convertor while serially connecting both device
or directly connecting arduino rx pin to my plc tx pin and vice versa will work??

How do u start a new post on arduino forum?

Can you tell us what a "plc ml-1400" is?

If you have one of these Micro Logix 1400 PLC, why would you need an arduino? User Manual Reference Manual

RS-232 is -10V to +10V (ie +-15V swing)
Arduino is +5V device signalling 0V-5V RS-232. So you need a level shifter IC to switch the 0V-5V to a +10V -10V RS-232 Standard level.
The device to look at is a Maxim Integrated circuits MAX23

MAX232 - Wikipedia Wikiepedia description TI MAX232 Data sheet 16 pin chip
MAX 232 Application Circuit Image
Google MAX232 and see what you can find for circuits and images.

Glad to help answer your question from Oregon USA, Fred