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Where to find Modbus connector pinout?
Looking for pinout info on Modbus
By Tim Greif on 30 April, 2002 - 2:17 pm

I need to know where to look to find the pinout for a Modbus cable 9-pin D connector for the Modbus port on a Momentum or Quantum plc. I've searched the modicon site and got no answers. The only helpful info I found is that they recommend a Belden 8777 cable whic is a three pair cable. How many of those conductors are actually needed to successfully interface with the modbus port connector on the plc?

Thanks for the help.

By Mont Coburn on 30 April, 2002 - 3:22 pm

The Modbus pinout is the same as RS232C. Its a standard found in many publications.

Good Luck

By Anonymous on 30 April, 2002 - 4:26 pm
1 out of 1 members thought this post was helpful...

<PRE>
IBM PLC
CD 1 *-1 SHLD
RX 2---------3 TX
TX 3---------2 RX
DTR 4--------6 DSR
GND 5--------5 GND
DSR 6--------4 DTR
RTS 7-| |-7 RTS
CTS 8-| |-8 CTS
9 NC

* Shield connection.
Jumper 7&8 on both
</PRE>

By Fernando Capelari - Schneider Electric Brasil on 1 May, 2002 - 3:50 pm

The pinout of the Modbus conectors, even for Momentum or Quantum, is part of the CPU manual, which is available for download at "www.modicon.com":http://www.modicon.com .

By Brad Hite on 1 May, 2002 - 4:07 pm

Hello Tim,

<P>Momentum Cable:
<P>Remember that the Momentum processor uses an RJ45 connector. </P>
<P>The cable pinout below is for the RJ45 to 9 Pin Female connector. The RJ45 cable between the connector and processor is a "straight through"
cable.</P>

<PRE>
-------------------------------------------------------------
PC End for Micro and Momentum controllers

RJ45 9 Pin
end Female End
---------------------------
6--|
2 ------------------ 4--|
3 ------------------ 2
4 ------------------ 3
5 ------------------ 5
6 -----|
7 -----| 7--|
8--|
</PRE>

<P>RJ45 Cable is a straight through cable.
Diagram below is looking at connector on cable.</P>
<PRE>
__________
| |
| |
| |
-- --
pin | | pin
1 - - 8
| |
----

____________________________________________________
Quantum and 984 Cable:

9 Pin to 9 Pin Modbus cable for Quantum and
984 processors with 9 pin Female Modbus ports

9 Pin 9 Pin
Male end Female End
Quantum PC
---------------------------
1 ------------------ 1
2 ------------------ 3
3 ------------------ 2
5 ------------------ 5
4 ---| 4--|
6 ---| 6--|

7 ---| 7--|
8 ---| 8--|

</PRE>

<P>Bradley G. Hite
<BR>Intertech Incorporated
<BR>mailto:bhite@myplc.com
<BR>http://www.myplc.com
<BR>Teaching Practical Skills for a Technological World</P>