Schematic for a RS-232 to DH-485 converter

[tico70]

Hello,

Does any body has the schematics for a RS-232 to DH-485 converter?

I need to connect a SLC500 PLC to my laptop but I dont have the cable, and I think that it will be very expensive to buy it form Allen Bradley.

Thanks in advance

 

[tom324]

dh-485

Does any body has the schematics for a RS-232 to DH-485 converter?
I need to connect a SLC500 PLC to my laptop but I dont have the cable, and I think that it will be very expensive to buy it form Allen Bradley.

It has been a while since I had contact with Allen Bradley's DH-485 so I am writing from memory. DH-485 is a propetary protocol which is working on RS485 interface; and RS-232 is a electrical interface (or standard, to be more precise). You probably mean RS232 to RS485 converter to connect the PLC to the laptop, but that will not work unless there is support for DH485 protocol on laptop.

RS-232 to DH-485 converter is electrical converter AND protocol converter.
Again, I am writing this from memory, so do not take it for granted.

Tom

 

[techie]

convertidor rs232 a dh485

Its been a while for me as well. But as far as I remember, the Rs-232 to DH-485 conevertor is just an electrical conevertor and all the support for DH-485 comes in software. I suppose tico70 has the software in his laptop already. So you would just need to build the convertor. DH-485 used a 6 pin connector but it wa just an extension of the 2-wire RS485 where the rest of the 4 conductors were used either as ground, shield or used to put a terminition 120 ohm resistor.
To make the Rs232 to 485 conversion, you will require a direction sensing arrangement since RS.232 is full duplex and DH-485 is half duplex sharing the same wires for tx and rx

 

[tico70]

dh485 to rs232

Thanks for reply.

Teachie, when you say software are you talking about the RSlogix500 or the RSlink. ?

I am downloading both form the net,so it will take a while because not all the people uses it

 

[techie]

dh485 protocol

Frankly I dont remember now. It's been more than 8 year now. I uses some DOS based program then. But I think you are right. If you use a software intended for communication with SLC500 over DH-485, then you should theoratically be able to use any 232to485 convertor to talk to that PLC.

 

[Emblema]

pin to pin dh-485

About 2 years ago I've found a forum (I don't remember its link) with following text:

If you personal want to play around with AB SLC500 without buying the PIC from AB, you can make one in cheaper price. The following is what you need:
a) RS232->RS485 converter. I'm using IC-485SI.
b) RJ45 plug.
c) min. 4 core screen cable for connecting between the Converter and the RS45 plug.
i) Connect terminal 1 (T+), terminal 4 (R+) on conv. to pin 1 of RJ45.
ii) Connect term. 2 (T-), term. 3 (R-) on conv. to pin 2 of RJ45 plug.
iii) GND on converter to pin 4 & 7 of RJ45 plug.
iv) Shield connect to pin 6 of RJ plug.
Crab the RJ plug upright with the metal connector facing you, Pin 1 to 8 is counting from left to right.
Turn the switches on the converter to DCE and T-RTS/R-RTS.
It works fine with SLC500/01 through RSLinx and RSLogix500.
Good Luck.