SCADA to PLC and PLC to PLC communications

[Ico747]

This is absolute newbie question. Is it posible several VisiLogic PLCs to be Modbus slaves to SCADA master and the same PLCs to support Remote PLC DataCom. PLC and SCADA computer are physically connected by Ethernet. The reason for this is that I do not want exchange of data between PLCs to go via SCADA computer. I

[Phil Salkie]

You can have multiple data connections as long as you have multiple communications ports. For example, the V570 comes with two RS-232/RS-422 ports standard, one expansion slot for another 232/422 or Ethernet, plus a CANBUS port. The CANBUS port can be used for PLC-to-PLC communications, and the serial ports can be used for SCADA-to-PLC connections. You can also use the Ethernet port for multiple simultaneous functions.

[Ico747]

You can also use the Ethernet port for multiple simultaneous functions.

Tank you very much for your clarification! As stupid newbie I should ask again. Does your statement above means that a Vision PLC could be master for another PLC and at the same time slave for SCADA if PLCs and SCADA PC are in Ethernet network?

[linxchas]

Yes, you can establish up to 4 communication channels using Ethernet Sockets 0-3 with independent config setting and you can change configuration of each channel in run time.

[scott_white85]

Yes, you can establish up to 4 communication channels using Ethernet Sockets 0-3 with independent config setting and you can change configuration of each channel in run time.

i agree with linxchas. you can use ethernet sockets for up to 4 communication channels with independent configuration settings.

______________________________

Flotech Controls Pte Ltd - scada or supervisory control and data acquisition is a communication system solutions which provides management system integration. This is also using HMI configuration and controller hardware to support client needs and requirements.

[snobeasto]

Hey all,

 

I'm newb at this too. I have two plcs that need to talk to eachother. can they talk across a common router? one of the PLCs has a EWON router in the cabinet and the other has a switch. If so could anyone point me to an example of how to do it or at least some sort of start point.

 

Thank you

[Flex727]

I regularly connect PLCs together to communicate data between them. I usually use MODBUS IP when connecting by Ethernet. As long as the PLCs are on the same subnet, they will communicate with ease and are reliable. You don't even need a router, hub, or switch if there are just two PLCs - just a crossover cable. There are example projects for Ethernet communications that come with your Visilogic installation. Go to Help\Examples\ and drill down till you find "V280_Ethernet_TCP_MODBUS_IP_Master.vlp" and "V280_Ethernet_TCP_MODBUS_IP_Slave.vlp". The functions are the same for all of the Vision products.

[Jesus Franco Franco]

Hello from Mexico.
I would like to know, if I can host the web server of unilogic to a hosting as a web page.

[Joe Tauser]

This post belongs in the UniStream section.  Please start a new thread next time.

Yes, UniStream can host web pages from itself.  Look in the Help under "web server"

Joe T.

[Patrick]

So let me see if I have understood the above correctly : I can set up master socket and a slave socket that will function in parallel?  In effect I will have a master/slave hybrid?

I am building a system with 10 Samba SM70-J-R20's each of which have a slaved autonomous vehicle with additional onboard I/O. 

I am using Modbus TCP/IP for communications over wifi. 

So far so good.

I also have a Vision 1210 which will act as a "god" and can take over and control the vehicle by writing bits directly to the Samba, and the Samba then does its thing.

Please see attached one line diagram

I have been wondering how I was going to deal with three layers, "Master-Master", Master and Slave, if I have understood correctly then I can set up the Samba as a hybrid and the system should work.

I would be grateful for confirmation that this will, or will not, work before I sit down and start playing in Visilogic.

Thanks in advance

 

[Flex727]

Your description is not precise enough to know if this will or will not work. However, I'll reiterate what was said above. Each V1210 & Samba PLC has 4 sockets for ethernet communications. Each socket is one communications channel to communicate with one device at a time. Each of these sockets can be setup independently as master or slave to any 4 ethernet devices simultaneously. You cannot maintain simultaneous communications with more than 4 devices using MODBUS TCP from any single PLC. You can, however, communicate with up to 4 of the Sambas from the V1210, while having each of those 4 Sambas communicate with up to 3 other Sambas in any way you wish.

[Patrick]

Hello Flex, thanks for the rapid answer.

I will try to be clearer.  Each Samba / vehicle pair are stand alone and do not communicate with any other pair.  A simple master/slave setup using a single port

Occasionally, I want the vision to be able to read or write to one / several / all of the Sambas  e.g. send a start or stop signal to all of them at the same time (or in very rapid sequence)

If I set up one socket on the Samba as a master,  and a second socket slaved  to the Vision, I should be able to achieve this.

The vision can then be programmed to address messages to each samba in sequence.

Or at least that's what I was planning

[Flex727]

1 hour ago, Patrick said:

The vision can then be programmed to address messages to each samba in sequence.

Yes, but be aware that the process of disconnecting the V1210 from one Samba and connecting to the next can take time, maybe a couple of seconds. If speed is of the essence, then have the V1210 stay connected with up to 4 Sambas, and have those Sambas stay connected with all the others, and have them relay the message. That can happen very rapidly (probably less than 100 or 200 milliseconds, perhaps much less).

[Flex727]

Perhaps this will flesh out more what I was trying to say:

V1210 Master to Samba 1-4

Samba 1 is slave to V1210, master to Sambas 5 & 6

Samba 2 is slave to V1210, master to Sambas 7 & 8

Samba 3 is slave to V1210, master to Sambas 9 & 10

Samba 4 is slave to V1210 only

This still leaves an open socket on each of your Sambas and allows very rapid communication to all the Sambas from the V1210 (with the right code in each Samba).

Another consideration (still doesn't solve all problems, but makes things a little easier) is the V700. It has 8 sockets instead of just 4. And finally, the UniStream has unlimited sockets, so that is another option.

[Patrick]

Hmmm.

I had not taken into consideration the time to connect and disconnect, although it is quite speedy on the test units I have.

The only problem with the relay idea is that if (for example) Samba 2 is switched off for maintenance then the message will not be passed along.

I have already purchased all the hardware, but considering the above I will get a quote for a Unistream tomorrow.  That seems to be the only way of doing this without a complete rethink unless you have any other ideas?

 

[Flex727]

If your test setup runs fast enough for you, then that's obviously better info than my estimate.

The right code can overcome one of the Sambas being off, but the permutations might get overwhelming.

A UniStream will definitely be able to maintain a MODBUS TCP connection to 10 Sambas simultaneously.

[Patrick]

Thanks for the advice Flex, much appreciated.

One last question, could this have been avoided if I used a different communications protocol and the subsequent choice of an Ethernet network between the Sambas and the Vision/Unistream?

 

[Flex727]

Did you consider MODBUS RTU?

[Patrick]

I did, and decided on TCP/IP because it is faster.  Oh the irony !

I could still buy 10 serial ports for the Sambas I suppose, but that would cost me half the price of the Unistream, plus I have already pulled all the Cat6 and I would lose the ethernet port.

On the other hand I also have CANbus cards for the Sambas in stock as I was planning on using them for something else, and then changed my mind.  Could I use CANbus between the Vision and the Sambas?

 

[Patrick]

I have been looking through the online documentation for CANbus and UniCAN.  Looks promising

[Flex727]

The V1210 supports UniCAN right out of the box, but I think you have to buy a module for the Samba. I also don't think you can run both UniCAN and Ethernet simultaneously on the Samba, but you'll need to check me on that.

[Patrick]

Ethernet and UniCan is OK, I can not do RS485 or 232 and Ethernet at the same time

Still reading the UniCAN docs on the Unitronics site at the moment

[Flex727]

2 minutes ago, Patrick said:

I can not do RS485 or 232 and Ethernet at the same time

Where did you see this? I don't do many projects with Samba, but I don't think that's true.

[Patrick]

https://unitronicsplc.com/samba-series-samba7/#1449515771593-63d974b6-05ac1451602511853

On the communications tab at the bottom, and also the local salesman told me

It is a bit misleading, but it it is 1 Serial OR Ethernet and CANbus

 

[Flex727]

I think that means a second serial port - there's one built in.