RS-232 cable connection for PLC and microcontroller

chintan12 · Apr 6, 2013

HELLO FRIENDS
i am very new to serial communication so i want to ask a basic question

i am communicating MICROLOGIX PLC(which have DB-9 serial port) with micro controller serially and as i know that microcontroller have TTL level signals
i have bought a RS-232 to TTL Converter

now my question is which cable i should use for connecting PLC to RS-232 to TTL Converter??
will it be a straight or cross cable??
please also tell me the connection

thank you so much in advance

FitzWilliam · Apr 6, 2013

Try a female-to-female null modem cable...You should be able to get one at your local Radio Shack. Normally, the Micrologix is programmed with an Allen Bradley # 1761-CBL-PM02. You might find a used one at www.theplccenter.com

Mark- · Apr 6, 2013

Hello,

Or purchase a cable from:

http://www.ind-concepts.com/Allen_Bradley_PLC_Cables.htm

Ken Roach · Apr 6, 2013

Since you said the MicroLogix has a DB9 style port, you do not need the A-B cable, which has a round mini-DIN8 connector.

Use any general purpose "null modem" cable, or a straight-through cable with a null modem adapter.

chintan12 · Apr 7, 2013

thank you so much to all for intrest in my post

i will make my own null modem cable and try

still i have little doubt
my friend just told me that no need to do soldering of whole null cable
just 3 connections which i described bellow will work

PLC(db-9) CONVERTOR (db-9)

2 ----------------------- 3
3 ----------------------- 2
5 ----------------------- 5

is it correct????

geniusintraining · Apr 7, 2013

Mark- said:
Hello,

Or purchase a cable from:

http://www.ind-concepts.com/Allen_Bradley_PLC_Cables.htm

Thank you kind sir

chintan12 said:
is it correct????

Yes 2&3 are send receive and 5 is common, BUT you do not need a TTL for the communication its is RS232 to RS232

If these is a DB9 then you are using a LRP processor on a MicroLogix 1500 or is this a 1400 CPU?

bernie_carlton · Apr 7, 2013

GIT - the item he is connecting to - the 'microcontroller' - has serial TTL. He knows that the PLC has RS232.

chintan12 · Apr 7, 2013

i have ML-1400 CPU

and as i know that microcontroller have ttl level output so i am puuting a RS-232 to TTL Converter in between

geniusintraining · Apr 7, 2013

bernie_carlton said:
GIT - the item he is connecting to - the 'microcontroller' - has serial TTL. He knows that the PLC has RS232.

Hi Bernie,

Too many micro's, guess I need to read a little closer

RS-232 cable connection for PLC and microcontroller

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