Allen-Bradley Communications

[CENTER]

I was wondering if any one has any ideas how I can set up 2 process controllers that communicate with either RS232 or PROFIBUS to my existing system, made up of a
AB PV 1500 Plus touch screen and a MicroLogix 1764 LRP Processor. I would like to set a bit in each process controller from the recipe in the PV.
I have seen equipment on line that from a Ethernet device I can have 4 RS232 ports but with the price of the AB Ethernet card and the 4 port unit it would be an expensive experiment and is beyond my scope. So any ideas would be appreciated.

 

[Ken Roach]

Tell us more about the process controllers, in particular what protocols they use on RS-232.

Since the 1764-LRP has two serial ports and you have it connected to a PanelView Plus, I presume that connection uses DF1 Full Duplex protocol on one of the RS-232 ports, leaving the other port open.

The most likely method is going to be an RS-232 "port splitter" and a serial protocol like Modbus RTU.

 

[CENTER]

It can work with two protocols as follows:
Standard
No parity
No flow control
Data bits=8
stop bits=1
Alternative
No parity
No flow control
Data bits=7
stop bits=2

 

[CENTER]

I am trying to get the rest of the protocols, and I will post them.

 

[Ken Roach]

Those are "serial framing" settings; they refer to the speed, number of bits, and basic error checking (parity) settings for the serial port.

The "protocol" is the language the devices are speaking. Typical examples in industrial automation are Modbus, ASCII, DF-1, etc.

 

[CENTER]

Rs232 Protocols

Sorry for the delay.
The only other info I have is that it mimics PROFIBUS

 

[Ken Roach]

Thanks for posting that protocol description.

What that looks like to me is a simple ASCII protocol, but I can't be sure: was that copied from a user manual or was it really written that way ?

A better way to describe a protocol like this is to give examples in ASCII or in hexadecimal.

From what you've posted, these process controllers don't appear to be addressable: There is no Address or Node Number field. That means you're going to need either a physically switchable Transmit pin, or a 'code operated' serial switch.

Can you tell us more about these "process controllers" ?

Do you need to only write to the process controllers, or do you need to read from them as well ? It might be necessary to do both to be sure that the data got through, as the protocol does not appear to have any Acknowledge or error check mechanism.

 

[CENTER]

That is from the user manual. I only have to write one bit to each unit. I can just move it from were I have it stored in my logic to the units.The manufacture would like to sell me 10 more units so I am shure I can get help with the coms but I need to be shure I can supply the hardware.

 

[CENTER]

And by the way that is the way it was written. Now I have googled switches but was looking for one that I could switch with a input. Just thinking it may be easier. I did see manual and programmable ones. The questionn is now I will not have a port to monitor the program if the occasion arises. I can disconect the switch or the hmi to download but that is it. Is there any merrit in looking into the Profibus network?

 

[Ken Roach]

I could have sworn I posted another entry about this. Strange.

I hadn't looked at Profibus because you were so cost averse with the Ethernet stuff, plus I have a general aversion to Profibus.

ProSoft Technology's Profibus DP master for the 1769 bus is moderately expensive but it might be easier than trying to learn the ASCII character set and install a serial switch.

 

[bce123]

maybe some info on

2 process controllers

could help. like model/make

 

[Ken Roach]

A Recommendation on Device Details

CENTER, since you're fairly new on the Forum, this thread is a good place to do some general-purpose commenting.

You can be fairly sure that specifying a popular PLC controller will allow people familiar with it to enter the discussion. "SLC-5/03" is often plenty of information, while "Allen-Bradley PLC" is not, and "1747-L531 OS302 FRN 11" might be overkill.

Less popular or obscure devices need more detail, preferably by a mix of direct posting and links. If you can tell me these are ACME Company Model 12 temperature controllers, model AC12-P, that's great. If a link to the company's literature website is available, even better.

The threads that make me grumpy are the ones that omit information intentionally, or make me have to spend a bunch of time with Google and the vendor website just to get on the same page as the poster. Untidy vendor websites often aggravate the problem.

You're doing pretty good: if you don't have easy links to the process controller's website or manuals, that's OK. But if you do, it frequently helps to include them in your initial post.

 

[CENTER]

Ok bear with me I still learning how to use the forum.http://www.protonproducts.com/cs_series.php The info I copied was really every thing that was in the manual. The model is a CS2G