Connecting to DH485 port on SLC 5/03

Eradicated

Member
Join Date
Sep 2013
Location
Berlin
Posts
9
Hello everyone, I have a question about connecting to an S500 PLC.

I have been tasked with going to site and taking a backup of a program from an AB S500-series PLC (5/03 processor, actually a version by ProSoft with built-in Modbus Slave functionality).
I have never worked with these PLCs in the past and have very limited experience with Allen-Bradley in general.

I have the software (RSLogix500 Pro and RSLinx), so I should be good on the software side of things.

However, there are two ports on the PLC:
1) RS232 Port (standard DB9 connector)
2) DH485 Port (8P8C/RJ45 connector)

I know I could use either of these to connect to it, however the RS232 port is in use all the time, i.e. it is configured as a Modbus slave and a SCADA system uses it to retrieve data from the PLC. I might not get the permission to disconnect it during my site visit, so I might have to use the DH485 port.

Now the main questions:
a) Can I use a standard USB-to-RS485 converter to connect to the PLC using the DH485 port, or is it a different electrical interface? In other words, do I need a dedicated cable from AB or can I use a generic RS485 one (like ADAM)?
b) If I can use a generic RS485 adaptor, does anybody have a wiring diagram that I could use to connect to this port?

I would appreciate your help!
 
Last edited:
a) Can I use a standard USB-to-RS485 converter to connect to the PLC using the DH485 port, or is it a different electrical interface? In other words, do I need a dedicated cable from AB or can I use a generic RS485 one (like ADAM)?
b) If I can use a generic RS485 adaptor, does anybody have a wiring diagram that I could use to connect to this port?

Hello,

No its not RS485 its DH485.. the part number you need is a 1747-UIC, if you can not find them locally we sell them

If you have a serial port on your PC you maybe able to use a 485/232 adapter but not if you are trying a USB also
 
Ok, thank you for the info.

It is a pity, though - I know that DH485 is really just a comms protocol which can utilise different physical interfaces.

I was hoping that the RJ45 port on that CPU really uses RS485 as the electrical interface, but if I need a dedicated adaptor, then it seems it is an AB proprietary interface of some sort?
I will have to search for the adaptor on eBay, then.
 
Ok, thank you for the info.

It is a pity, though - I know that DH485 is really just a comms protocol which can utilise different physical interfaces.

I was hoping that the RJ45 port on that CPU really uses RS485 as the electrical interface, but if I need a dedicated adaptor, then it seems it is an AB proprietary interface of some sort?
I will have to search for the adaptor on eBay, then.


DH485 is both electrical(RS485) and protocol(DH485)

The above mentioned 1747-UIC is both a electrical converter (USB to DH485) and protocol converter (DF1 to DH485)

There is no driver in RSLinx that would support the Adams (like) device. That I know of.

AB gurus please correct me if I'm wrong.
 
Last edited:
Some of the Allen Bradley legacy cables are quite expensive. If you're lucky you might be able to get away with using a USB to Serial connector like what is used for Micrologix 1200's connectors (RS232 to DB9 Connector) they are much cheaper. I know you said that port is in use but I think it's probably your better option. Two $20 cables instead of one $70 to $400 cable https://www.plccable.com/allen-bradley/ I think the ones you want are on that page and the AB Factory sealed one's price is kind of ridiculous.
 

Similar Topics

Hi all, I have a SLC 5/02 that's been gathering dust for the past couple years that I want to have some fun with. The only problem is I don't...
Replies
9
Views
3,850
Dear Folks, I have to trouble shoot a panel which have one SLC 5/03 PLC and one PV550. I can communicate with SLC 5/03 using USB to RS-232. But...
Replies
5
Views
4,684
Hello all, I had an old machine come back in for some work. The system has an SLC 5/03 which connects to a PanelView 600 through it's CH0...
Replies
4
Views
8,156
I am working on project where I have to connect one SLC 5/03 to Two Workstations and two MODBUS controllers, on DH485 NETWORK. I am using protocol...
Replies
1
Views
3,515
Hi everyone, I have a slc 5/03.. and this one uses the dh485 for communication. It currently has a pv 550, also using he dh485...
Replies
4
Views
1,995
Back
Top Bottom