SLC 5/03 RS-485 network

[alexbeatle]

Good day!
I'm having trouble understanding the concept of building specifically AB RS-485 network. As far as I know, SLC 5/03 processor has a RJ-45 connector used to connect straight to the RS-485 network (proper electrical signals are formed (checked)), and mainly DH485 protocol network. But everywhere I look it is either suggested to use RS232 (DH485 protocol) and then convert it using AIC+ to the required RS-485 differential signal, or explained how to communicate PC with PLC through RJ-45.
Again, what I'm after is connecting several PLCs (with SLC 5/03 CPU), PanelViews, etc. on RS-485 network.


Thank you

 

[Mickey]

See link below for the manual. ( Appendix B)

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1747-um011_-en-p.pdf

 

[bernie_carlton]

A single local device to device connection can be made between two DH485 devices using the RJ45 port. This is fine when the devices are in the same cabinet (HMI to PLC) to PC to PLC for programming. This is not a network.

The 1761-NET AIC (old isolator) provided the necessary (transformer I believe) isolation between the components in the SLC 5/03 and those in remote devices. Grounding differences are minimized because of the isolation.

For those devices which have only RS232 but can use the DH485 protocol the NET-AIC+ provides electrical transformation and isolation.

Connecting a network strictly by the diagrams is always recommended. For the SLC 5/03 use the communication diagrams in its manual. (I see that Mickey provided a handy link.)

I hope this helps.

 

[alexbeatle]

Does this mean (according to the SLC 5/03 manual (p.193) supplied by Mickey), if I'm to use multiple devices on the network, I need to attach each device to the 1747-AIC, and run the communication cable between these interfaces?
The reason I'm asking is that the Belden #3106A cable suggested by the same manual only has connections for Data+ (A), Data- (B), Signal Ground and Shield, when SLC 5/03 also has the Transmission/Reception control output (required to establish non-colisive communication), and +24VDC.

 

[bernie_carlton]

Follow the manual precisely. The Transmission/Reception control affects the interface. it doesn't go out on the network. Once a master on an RS485 network sends a command it must place the sending chips into an OFF state to allow the return answer. When attached in a one - to - one configuration it turns off its own sending ships. But when attached to the network interface it must turn it off also.

 

[kirk]

In my opinion the pic driver is the most temperamental connection in rs linx.

It wont run in linx as a service , it has to bet up as a utility (or something like that).

In order to get it to work it think it may be necessary to cut the head off of a live chicken under a full moon and do a dance counter clockwise with a bare chest and hopping on your left foot.

When i have set these up the problems always revolved around setting up the pic driver. The wiring is a pretty straight forward serial connection.

BUT, when you get it configured it works ok.

 

[alexbeatle]

Thank you very much everybody.
It just seems a little unusual that the device (PLC) has the RS485 interface, but still requires an additional device to actually put it on the network!