Very SImple Messaging Question

[METSYSTEM 1]

Can someone please answer what I believe will be a very simple question... Am I able to set up message instructions between a control logix plc using AB_ETH1 coms path and a compact logix plc using AB_ETHIP1 coms path? The two plcs are sat on a fibre network and my terminal can connect to each using their respective drivers. The HM spider switch that the 2 controllers are connected to, have different channel status lights showing. This is what makes me question myself?? The Compact Logix that uses AB_ETHIP1 path has status: 100/10 led = on Link/Act = on (My computer connection also shows this when connected) The Control Logix that uses AB_ETH1 path has status :100/10 led = OFF Link/Act = on This will probably get a few laughs but if someone can help Id be grateful Regards Alex

[Ken Roach 194]

It's a good question ! RSLinx Classic can use either the "Ethernet Devices" driver or the "EtherNet/IP" driver to communicate with CompactLogix and ControlLogix systems. The differences are subtle, but in short, you can use either one. RSLinx will not be part of the path between the CompactLogix and ControlLogix. What interests me is the 100/10 LED on the switch connected to the ControlLogix. Is this using an old 1756-ENET module, or a modern 1756-ENBT or 1756-EN2T module ? The old -ENET modules were 10 mb/s half-duplex only, while the modern modules support 100BaseTX with Auto-Negotiation. If the ControlLogix is using a modern module but still has the 100/10 Mb LED turned off, then there's a problem with the switch configuration or the cable. I believe that Hirschmann SPIDER switches are un-managed; is that correct ? To determine the "CIP Path" to use between the two controllers, you need to know the IP addresses of each controller's Ethernet interface, and the Slot Number where the ControlLogix CPU is installed. Will you be triggering the MSG instructions in the CompactLogix, the ControlLogix, or both ? Have you considered using Produced/Consumed Tags instead ?

[METSYSTEM 1]

Firstly, Thank You for responding, I will check on site tomorrow to see which processeor the Controllogix uses. The Hirschman is unmanaged. However, the control logix end has another hub/media converter that takes the site fibre conection. The Compact Logix is on an ethernet spur from that hub. The hirschman just provides the extra local access port. I was going to write from the compact logix using a CIP Data Table Write instruction? If you have a minute to explain Produced/Consumed Tags I am always open to ideas as I am relatively new to this game. Once again thanks Alex

[BobLfoot 301]

Alex - welcome. As your "new to the game" please allow me to elaborate a little on what has been suggested. 1. Produced/Consumed tags are setup when the program is written and establish a link between 2 processors that updates "in the background" without the need for message instructions. They have several advantages over the message approach. 2. When you are forced to used message isntructions {adding a new handshake "on the fly" to a system you can't stop for example} keep the following simple example in mind for reads versus writes. 2a. The read involves two phases - Phase 1 the PLC to receive data asks for it. Phase 2 the PLC with the Data Sends it to the one requesting the read. READ is now Done if error free or done again if not. 2b. The write involves four phases. Phase 1 the PLC writing the Data asks for permission to send. Phase 2 the PLC receiving the data gives permission for data to be sent. Phase 3 PLC doing writing sends the Data. Phase 4 PLC receiving the data confirms that it was error free. Write is not Done if Error Free or repeated if not. May not seem like alot but have 20 devices all writing versus 20 devices all reading and you'll see a performance difference most likely.

[Ken Moore 23]

Take a look at this article in the download section: http://forums.mrplc.com/index.php?app=downloads&showfile=710

[waterboy 7]

Can you force both ports to 100mb? My Hirschmann didn't recognize the 100mb requirement of my Cisco router and I had to force the port speed before it would work. Perhaps a similar signalling issue exists here.

[waterboy 7]

HUB?? Say it isnt so. Hubs are hDX. Hopefully you mean a switch?

[Conor 4]

Hi Alex, I had a lot of issues in my plant when using unmanaged switches. They guys here were great help and also my local rockwell tch support guy was good too. Basically I have got rid of all my unmanaged switches. I know that this is going a little away from your original post but I thought that this is an important issue going forward with your plant network. Also, as per what waterboy says make sure your plc speeds and duplex settings are all the same. I have standardised on 100 Mbs Full duplex. This may not be an issue with the newer AB plc's, but I know from experience that the plc5's and slc's need to be forced to these settings. Conor

[OkiePC 14]

Also be aware of the differences in network demand between an occasional message and a listen only I/O connection or a consumed tag. Managed switches between the devices on the same subnet with ONE IGMP Querier and IGMP Snooping turned on for the affected ports/switches. I think the Spiders are unmanaged swithces for local stuff, intended to be connected to the RS series (we use Hirschmann RS-20 with great success on the controls LAN). No hubs, no office style stuff, it will cost you money more than enough for a managed switch or two. The port speed is an issue, it's been a problem with us too, we were told to force ports to 100Mb/Full Duplex by rockwell FTView experts. Also we still have two old SLC 5/05s stuck at 10mb/half, causing us to have to force port speeds to avoid periodic boostrap logic in the more modern ethernet switch from trying to renegotiate a faster speed. Monitor your communications channel status words (the Logix device webpage is great for this when available) too. Edited 10 Oct 2011 by OkiePC

[daba 4]

AB_ETHIP1 and AB_ETH1 are drivers you set up in RSLinx on your PC to talk to the hardware No-one has actually stated that your intended messaging does not have anything to do with these drivers. These drivers exist within RSLinx only to allow the PC to communicate with the hardware. As already stated, the controllers will use CIP Paths to find their target for the message, and all that is needed is that the devices have the same network parameters, i.e. speed and duplex settings.

[OkiePC 14]

Going further, the IP addresses and subnet masks of the PLC comm ports must be compatible and there must be network connectivity between the two PLCs. RSLinx is a separate connection to your PC which must also have a compatible IP Config in order to connect to the two PLCs which can happily carry on "MSGing" each other as long as there's copper and "happy lights" on devices between them. EDIT: I see Ken did cover this, but he summarized a lot more too, but I will leave it since he didn't get into the details of subnet masks and IP addresses which the OP should report. Edited 12 Oct 2011 by OkiePC