Controllogix to RS232/RS485?

In the Controllogix system I am doing for a vacuum furnace.....
I have 2 devices that only have RS232 for communications and 1 that is only Modbus RTU on RS485.
I am planning on buying (2) RS232 to RS485 serial converters for the RS232 devices so I can have all devices talking RS485 on 1 line.

Don't want to sound too dumb here, but I have never done Modbus RTU only Modbus TCP.

Will I have an issue with the Modbus communication to the RS485 device? If I talk ASCII to the other devices will i be able to talk Modbus RTU to the other device?

Now to talk Controllogix to serial RS485 and/or Modbus RTU.

The 1734 RS485 Point IO module I was going to use, I now find is for Devicenet only and will not talk ASCII.

Any Ideas....I am using Ethernet/IP between all my Controllogix devices, VFD, and 1734 Point IO racks, so that is my preferred method of comms.

Should I just go to Anybus and get an Ethernet/IP to ASCII gateway?
I heard Anybus makes good products.

Has anybody used *******'s "Devicemaster UP" gateway?
http://www.*******.com/pub/en/ethernet-ip-to-serial-device-communications


Maybe someone has a better idea?

How come Anybus is not *** out but the other vendor (hint...c-o-m-t-r-o-l) is?

How about a Prosoft Modbus module? They work very well, but aren't cheap.

I can't tell why C o m t r o l would be a problem.

I have a lot of experience with this sort of thing.

The 1734-232ASC and 1734-485ASC work with any network adapter: I have used them with EtherNet/IP several times.

The protocol is important: they work well when there is text with delimiter characters, but not so well with binary protocols.

Prosoft showed a POINT module for Modbus RTU at Automation Fair, but I don't know if it has been released yet.

The AnyBus Communicator is good, as are the Prosoft standalone gateways.

I just did a project with the GridConnect Net485 to Modbus RTU over EtherNet/IP. It requires much more skill to set up but is a nice simple inexpensive device.

Ken Roach said:

I have a lot of experience with this sort of thing.

The 1734-232ASC and 1734-485ASC work with any network adapter: I have used them with EtherNet/IP several times.

The protocol is important: they work well when there is text with delimiter characters, but not so well with binary protocols.

Prosoft showed a POINT module for Modbus RTU at Automation Fair, but I don't know if it has been released yet.

The AnyBus Communicator is good, as are the Prosoft standalone gateways.

I just did a project with the GridConnect Net485 to Modbus RTU over EtherNet/IP. It requires much more skill to set up but is a nice simple inexpensive device.

Click to expand...

"The 1734-232ASC and 1734-485ASC work with any network adapter: I have used them with EtherNet/IP several times."

Sorry I was not clear here.
I know I can talk Ethernet/IP to the 1734-485ASC, it is the other side of the module (RS485) that worries me, as I understand from AB, it can only be set up as a Devicenet object thru RSworks. I despise working with Devicenet, and do my best to stay away from it.

Can you talk RS485 Modbus RTU to 1 device and RS485 ASCII to another device across the same communications cable??

as I understand from AB, [the RS-485 side of the 485ASC] it can only be set up as a Devicenet object thru RSNetWorx.

Click to expand...

They must have misunderstood the application. All of the features, functions, and parameters of the 1734-232ASC and -485ASC are available via RSLogix 5000 when used with ControlNet or EtherNet/IP. RSNetworx is necessary only when you are using DeviceNet.

It's theoretically possible for both ASCII and Modbus RTU to share the same wires, but in practice it would be very difficult.

Ken Roach said:

They must have misunderstood the application. All of the features, functions, and parameters of the 1734-232ASC and -485ASC are available via RSLogix 5000 when used with ControlNet or EtherNet/IP. RSNetworx is necessary only when you are using DeviceNet.

It's theoretically possible for both ASCII and Modbus RTU to share the same wires, but in practice it would be very difficult.

Click to expand...

According to AB the 1734-485ASC module is for Devicenet communications and will not talk RS485 ASCII.

According to AB the 1734-485ASC module is for Devicenet communications and will not talk RS485 ASCII.

Click to expand...

Either you are talking to somebody at A-B who is unfamiliar with the product, or we're all using the wrong terminology. "RS-485 ASCII" is exactly what the 1734-485ASC serial side "talks". The POINTBus is very similar to DeviceNet, but the module can be used with both ControlNet, EtherNet/IP, or CompactLogix POINT I/O interfaces.

Let's talk about the ASCII protocol. Does it have 'delimiter' characters, like CR or LF or ESC ?

C o m t r o l spamming a bunch of junk advertising for the Device master.


You mught want to look at Real Time Automation. These folks make zome nice and easy bridge converters. I use several of their converters to put ASCII marquees on Ethernet I/P. A lot of other integrators keep saying it is not possible. I like those jobs al the way to the bank.

I am looking into RTA...probably the route.

From AB Knowledge Base:
"As there is no method of setting node address on the 1734-485asc module, it cannot be configured for a multidrop 485 network. The module will respond to all signals on the network thus, it needs to be a point to point network only."

..

Thanks, Nathan.

That's RA Knowledgebase article ID #47474 (Access Level: Everyone).

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/47474

That's sort of a weird note; ASCII doesn't have "node numbers".

The module has an ordinary RS485 port that would work fine on a multidrop network that had "listen-only" devices like text marquees on it.

What it won't do is attempt to ignore traffic that's "not addressed to it"; that's what protocols like Modbus are for.

An aside: I'm fine with you using whatever device you want; RTA makes an ASCII gateway that has a very strong reputation for ease-of-use.

It's just that you seemed to be getting bad info about the 1734-485ASC or getting in touch with folks who don't know the product. I know it very well and didn't want you or future readers of this thread to get mis-information.

Actually the problem grows. I cannot "node address" the RS232 devices, so i don't think they will work on RS485 in a "multidrop", they also will have to be point to point.

Here are the manuals on the (2) RS232 devices.
Yes, they are also available on RS485, but customer is presently using the RS232 devices as it comes standard and the RS485 option is 3 months out.
The RS232 communications info on the BCG450 starts on page 35.