Multiple Serial to Ethernet

Hi again,
I am currently in a project that require that we take 30 PLCs GE Micro (of 30 machines) to be connected to a PC server that will have a Web server system to administrate the machines, and make a logging of the data.
Form each machine we take some 100 registers and 100 bits (aprox.)
We are looking for some solutions to change the serial ports to ethernet and so gather all the information in the server.

Does someone worked with Virtual serial ports in one machine to 30 serial ports?

We try to use the Red Lion Data Station, connecting 2 machines in chained 485 and converting the SNP protocol to Modbus/IP,(we wanted 4) , but it is not working properly, with one PLC works fine, but when we add the second PLC it is way to slow, and we miss events and data. (That was our preferred solution, but is expensive if we use one DS to one PLC...

Does someone tryied the Modbus RTU to Modbus/IP bridges in projects with large quantities (~30) of devices?

Any other recomendations?

Thanks

sapoleon said:

We try to use the Red Lion Data Station, connecting 2 machines in chained 485 and converting the SNP protocol to Modbus/IP,(we wanted 4) , but it is not working properly, with one PLC works fine, but when we add the second PLC it is way to slow, and we miss events and data. (That was our preferred solution, but is expensive if we use one DS to one PLC...

Click to expand...

Every similar project I've been involved with (recently Chrysler's plantwide version of EMS) for fault monitoring/data required some canned logic installed in the PLC to buffer data for transmission up to a PLC concentrator or a PC DCS. I'm inferring from the post that your DCS was trying to monitor I/O in realtime. Though possibly workable for a small number of PLCs, I don't believe its the correct model to use for any system of size. The canned EMS logic was identical for a PLC family but the unique signals for each each PLC were mapped/copied into a pre-defined data block that the logic used for monitoring.

A true Equipment Monitoring System is not a simple implementation. Many years ago I was involved in monitoring over 200 PLC-2s on a body welding line that took almost 2 years to get up and running. Each PLC had to be studied for the signals to be monitored (faults, starved, blocked, etc) and then mapped into canned logic for streaming up to a Intellution Fix Dmacs system via a PLC-3 concentrator.

Hello Sapoleon,
There are two types of the Micro:
1. The older 14-, 23-, 28pt Micros
2. The new 20-, 40-, 64pt Micros, where you can add a nonexpensive Ethernet board what enables you to get a direct connection to your plant wide network.

The older controllers could be grouped (multidrop) and one Micro out of the group is connected to the VersaMax SE device (serial to Ethernet converter). Grouping is cost effective, but requires the wiring. Quicker implementation is with a VersaMax SE at each Micro.

Joern

hi,

The thing is like this, this is an upgrade that we are making in a plant that we work with for almost 9 years now.
All the PLCs have the same program, and the program is already optimized to transfer to a SCADA.
The reason for making the new configuration, is that in this moment, each machine have a CIMPLICITY station working with it, and there is a CIMPLICITY server that collects from the other PCs in the machines the data.
They need at this time to make an upgrade to all the system, and they are not too happy with the CIMPLICITY server. So they change that, but they don't want to pay the price for upgrade all the machines with CIMPLICITY (we are talking of 250 machines world wide).
The new system, runs with a big server, and then the operator screens are going to be web based. (It's a custom program).

Now, we wanted in the first place to use the serial to ethernet module for the GE PLCs, but, they are not cheap, and even the people from GE here told us that they are not good.

Our first attempt, was using the Data Station from Red Lion. It works fine with one PLC (expensive to use with just 1) and when we tryied to use it reading also a second PLC, we had delays too big.

The PLCs that we are talking don't run the machines, just make some fault control. There is some 40 registers that are time critic, but not the rest.
Those registers in any case, are a buffer, because the real response of the machines and the faults is too high.

In any case, we are again evaluating options... It can be another PLC, but i don't think it's the case, we will be talking again of 1 PLC every no so many machines to get the time requests. So...

1.Think about in replacing the existing Micros by the new VersaMax Micro 20/40 or 64 point. They have one serial port on board and the option to add a cheap ethernet board to the second port. Then you are able to connect to the Micros directly without any converter from a big Cimplicity server. The new Micro incl. ethernet board cost a few bucks. there is nothing to change in the program, just change the CPU in the HWCFG, configure port 2, assign the IP adress according GFK-2436 - thats it.

2. Keep the PLCs and collect the data in RS-485 multidrop from a Quickpanel View Intermediate. It provides the data without tag counting to CIMPLICITY and has an Historian collector in. This has the advantage to have a local time stamp and an data buffer which makes the data logging independend from network outages.

Ask your GE colleagues for pro and contras for your specific solution.

Joern

We have done somethin similar at our plant. We had several serial networks (RS-485/RS-232) that needed to be ethernet for data logging. I found these devices (http://www.bb-elec.com/product_family.asp?FamilyId=120&TrailType=Sub&Trail=1). I have the 2 port version and I find it works reliably. In your case, with 30 PLCs I would suggest getting the 4 port version (or 4 1 port models) and splitting your network up into segments. This should help with the congestion.

The reason I say as an alternative, get 4 1 port models is that you may be able to raise the speed of the serial network with a shorter distance run.

DeviceMaster UP

Our DeviceMaster UP product facilitates Modbus RTU to Modbus TCP communications. We have a 1-port and a 4-port model currently available. This would effectively offer you the connection of 4 Modbus RTU devices to a single physical Ethernet connection (communicating Modbus TCP). Using a switch and multiple DeviceMaster units, you can eliminate the need for multidrop if you prefer.

If you'd rather just have mutliple serial to Ethernet (NOT Modbus TCP), then we have a product called DeviceMaster RTS, which supports up to 32 serial ports across a single Ethernet connection.

Please feel free to call or email me if I can help with anything.

Hi,
Mammoth:
Tanks for your replies.
We already check with our GE representatives here, and the problem with the GE solutions, is the price. Our first attempt was to upgrade CIMPLICITY, and the costs where huge. Then add GE serial to ethernet, and they told us is no good. The last was to change the PLCs, but it was also expensive, andwe don't have what to do with the other 200 plcs that we are going to take out.
I will check now the Quickpanel View.

Christoff84:
I will start checking them, 2 days ago, I found a similar product that we are trying to check, and people that we have contact with use it also for a big project.
http://www.digi.com/products/serialservers/portserverts.jsp

Do you use it like a virtual com?

I have successfully used 2 off 16 port serial to Ethernet converters on a job talking to card readers in a car plant.
http://www.moxa.com/product/NPort_5600.htm

The ports map to virtual comports on the PC which is running Intouch. The only problem I had was the I/O server I was using could only address up to COM32. I use some eZmarquee message displays on the higher ports which I address directly.

Hello Sapoleon, I would go with Mammoths recomentdation. The Versamax SE is a protocol converter which will take convert the serial protocol to SRTP. Also if you get one per device then depending on how you get the data from them to your DCS you will now have the option of talking to all devices simultaneously.

We have customers that are reading 200+ devices in this manner and they are very satisfied.