SLC5/03 PLC

[mpc 0]

I have an old system to be upgraded recently. I would like to use (SLC5/03 + 1761-NET-ENI) for the ethernet communications. There are totally 20 SLC5/03 PLC involved. I saw there are some issues about 1761-NET-ENI module which stated that only six of them can communication at the same time. Did any body know if there is limitation for the NET-ENI module? Also I want to download program from PC in office to the different PLCs according to different IP address. How can I do that?

[Ken Roach 194]

The "six at the same time" limitation refers to the number of TCP connections each 1761-NET-ENI can support in a given direction at the same time. The actual limit is "4 incoming, 4 outgoing, and 2 either incoming or outgoing", for a maximum of six in one direction. Consider a system where a single 1761-NET-ENI had to send messages to several other controllers. It could create up to six outgoing TCP connections and still accept one or two incoming connections (like from RSLinx/RSLogix). But if you tried to send another MSG instruction from that same controller to a seventh controller, it would fail. If your system has a great number of peer-to-peer messages, like "every SLC sends a message to eight other SLCs" or "One SLC serves as a data concentrator and sends messages to 19 other SLCs" then the 1761-NET-ENI is not right for your application. If you have, for example, a SCADA system that will be making a single TCP connection to monitor each SLC-5/03 controller, then you have only one incoming TCP connection each and you're in fine shape. There are quite a few ways to get Ethernet access to these controllers. If your intent is only to give your Office PC access to the controllers, then you might not even need the 1761-NET-ENI and could use something like the Lantronix DR-1 or the Digi One Ethernet/RS232 converter. These products generally will represent the PC to converter link over Ethernet as a virtual serial port, so you would have 20 DF1 Full Duplex drivers in RSLinx. If the SLC-5.03 controllers are already connected using DH-485 protocol, you might get the functionality you need by bridging that network to Ethernet, like by using a 1756-DH485 and 1756-ENBT in a ControlLogix chassis, or using something from DataLink/EquusTek (www.protocolconverter.com). Tell us more about your application and connectivity needs.

[mpc 0]

Thanks, Guru. Is there any connection limitation issues regarding with the SLC5/05 PLCs.

[Ken Roach 194]

The SLC-5/05 will handle more TCP connections than the 1761-NET-ENI but it has its own limitations. The SLC-5/05's TCP connection capacity varies with the Model (L551, L552, L553) and the Hardware Series. The newest Series C hardware, which supports 10/100 Mb/s Ethernet, has more capacity than the earlier Series A and B hardware. I'll just link to the document instead of re-stating them here: RA Knowledgebase Answer ID # 17469. Tell us more about your requirements; is there just PC access, or a central data collector, or a lot of peer-to-peer functions ?

[mpc 0]

Thx, Ken. We have two lines. Each line has one master PLC function as a central data collector which need to communication with the other 8 PLCs in the same line. The only data exchange is between master PLC and other slave PLCs. There are no data exchange between the slave PLCs. There are total 18 PLCs on two lines and two exitsting standalone SLC5/03 PLCs. I checked the link you gave. Now the question is that can I choose SLC5/05 PLC as the master PLC and SLC5/03 + 1761-ENI-Net as the slave PLCs. Cause SLC5/03+ENI-NET is $2000 but SLC5/05 is $3200. Thx in advance.

[Ken Roach 194]

That's great information, thank you. This is one of those applications that the 1761-NET-ENI is specifically built to address. You could add 1761-NET-ENI modules to each of the line controllers and change out the "data concentrator" controllers for SLC-5/05 controllers. A new 1747-L551 controller has an equivalent memory (16K) to the 1747-L532 controller and supports 32 TCP Connections; 4 incoming, 4 outgoing, and 24 either way. The most efficient way to handle the traffic would be to have each -ENI equipped controller send a message periodically or on-event to the data concentrator. If each line has a data concentrator, it would only be handling 8 incoming TCP connections. An alternative way to collect this data would be: 1. Link each 9-controller system with DH-485 trunk cable and equip each SLC-5/03 controller with a 1747-AIC link isolator. 2. Replace the data concentrator controller with an SLC-5/05 and connect a 1761-NET-AIC converter/isolator to its Channel 0 RS-232 port. 3. Program MSG instructions to periodically send data from the 5/03 controllers to the 5/05 controller over the DH-485 network. 4. Collect that data over Ethernet from the SLC-5/05 controller. This assumes that your controllers are within about 4000 cable-feet of one another and that it is not prohibitively expensive to run cable between them. This will not be as fast as a full-Ethernet system, but will cost about 1/2 as much in hardware.

[JeffKiper 9]

Ken do the 5/03 have bridging between ports? If so could he use 1 ENI on the master and bridge to the others. mcp said tha the master talks to the slave unit so I ASSuME they are talking 485. I have used the 5/05 as bridge to a AIC network once it worked nice.

[mpc 0]

Hi Ken, When you mention that using DH485 to replace the ethernet between these PLCs , do you mean there is no limitation for the 1747-AIC link isolator to communicate with other device? If this is the case, I will consider it. Another requirement is that we want to remote download the program to each controller from our office. Therefore we need to install some card on our PC to enable the DH485 protocol. I have one more concern is about the panelview. We plan to use three panelview + CE on each line. They are displaying the same screen at different locations. Does it support a server client structure that we can use or must all mounted on the network? If each one need a connection and we use ethernet, does it occupy one incoming connection and one out connection? Also we try to find some OP which has the webserver function, then we can use it IE from office remotely monitor and control the OPs.

[Ken Roach 194]

Data Highway 485 is a token-passing network, so there's no "connection management", just a network that chugs away and delivers messages as they come along. You could happily have a single controller sending messages to 30 others. DH-485 networks support only 31 nodes, but the performance of the network depends on the how much traffic is requested by each device. You can put 31 SLC-5/03s onto the same network, and if you are only going online with one of them at a time, you're going to have pretty good performance. If there is PanelView traffic to three of them and peer-to-peer messaging and you are going online with two simultaneously, traffic will slow to a crawl. Adding the operator interfaces into the system makes it a little more interesting. Definitely do not put the operator interfaces onto the DH-485 network if you can avoid it. Three terminals constantly reading data from multiple controllers would assuredly overload a DH485 network. If you can attach the operator interfaces to the Ethernet, things get a little easier. The SLC-5/05 will have an Incoming TCP connection to each operator interface, so that would only account for 3 TPC connections per SLC-5/05. If you don't try to read all your data at fast (1/4 second or faster) update rates, an SLC-5/05 can happily serve three PV+CE terminals. With regard to the webserver function; later this year, RA is coming out with "FactoryTalk ViewPoint", which will have a PV+ based version that lets the PV+ publish its displays to web browsers. It will support a single read-only client, and is aimed at casual remote users, not machine operators. The PV+ version is added to the PV+ firmware at no charge, but the FTView SE distributed version has pricing that expands with the number of simultaneous web clients (up to 50, I think). I expect this to be on sale in March or April 2009. If you bought "FactoryTalk View Machine Edition Station Runtime" license, you could run the PV+ runtime application on a desktop or laptop computer, using the exact same project that is running on the terminals in the field.

[mpc 0]

Thanks a lot, Ken. I am making a proposal to the client and I will post the network system on this site.