Frequently Asked Questions If you have a question that is not answered here, please contact our experts via our Personal Assistance Center. General Will the Server work on Windows XP SP2? Yes, the INGEAR OPC Servers will work on XP SP2. See our special site for more detailed information on how to set up your system for DCOM Communicaitons -- Licensing I have multiple machines I need to install this server on - how is the licensing handled? - Each OPC Server is licensed on a per machine basis so you will need a license for each machine. We do offer 5 packs of licenses that essentially give you 5 licenses for the price of 4. See the ordering information page for pricing and part numbers. If you have needs large quantities of licenses (> 20 in one order or large annual volumes), please email us at ingearopc@softwaretoolbox.com and specify the nature of your need, estimated volume (annual and in each purchase) and what OPC client application you are using. Windows CE For the Windows CE Version, what CPU's are you supporting? - As you may know, with Windows CE, there are a variety of CPU's that run that operating system. Some of the popular ones include the MIPS, Hitachi SH3, Intel x86, and Strong Arm. We are supporting the MIPS processor first followed by the Intel x86 and then the Hitachi and Strong Arm processors. Check with the manufacturer of your CE device to find out what CPU your device has. Contact us regarding support for your CPU if you do not see it listed. Since the Windows CE OPC server is an In-Process (In-proc) server, how do you configure your tag database? - We provide you with a utility to use on your desktop (win95/98/NT machine) to build the tag database file. You then download the tag database file from your workstation to the CE device and the CE device reads it at startup provided you have named the file according to the documentation. OPC Can you assign different polling rates to different groups of tags/items ? Yes, by nature of being an OPC server you can do this. In the OPC world, the OPC Client tells the server what the group update rate should be for each group. You don't configure it in the server's user interface per se. The client tells the server through it's connection what update rate to use. When the OPC client application connects to the server and subscribes to tags, the person configuring your client application can set an update rate for that group of tags. If you don't see this ability to configure the group update rate in your OPC client, let your OPC client vendor know they aren't playing by the OPC rules as was intended. How do you resolve scan cycles - when do you get fresh data from the PLC ? We look at the group update rates set by all clients and all the items the clients are subscribed to. We then optimize our reads so that we use the fewest transactions possible to the PLC over the PLC network. If you have 2 clients asking for the same data, one at one rate, say 500ms and another at say 2000ms, we're going to poll the PLC one time from the OPC server every 500 ms. We'll report updates to the one client every 500ms, then the other client every 4th update we get from the PLC in the OPC server or 2000ms. In OPC you can always request what is called a Synchronous read any time you want from the client. The Synchronous read tells the OPC server "I don't care when you polled last or when you are scheduled to poll again, go get me this data right now". Synchronous reads are of course slower than asynchronous reads for this reason and thus are typically only used when you need that high priority request. The norm in OPC is for clients and servers to communicate on the event driven asychronous basis for maximum performance and throughput. What happens if I'm talking to 10 PLCs over ethernet and one of the PLCs goes down - does the server bog down ? No. Every PLC connection will be running in it's own thread. That's the beauty of this being a true 32-bit multithreaded application. One PLC can go down and report timeouts and the other threads keep on running independent and unaffected by the one that isn't communicating.  How does the client application know when PLC communications are down ? OPC has a special feature called "data quality". When the OPC server reports back to the OPC client, it also passes back a data quality flag and timestamp for every item. These don't take that much bandwidth to pass but give you a great tool. If the last time the OPC server tried to read the PLC it got a response then data quality is set to Good. If the PLC didn't respond then the client gets data back from the OPC server in the form of the last value read from the PLC but the data quality is set to bad. This tells the client "don't trust this data, I didn't get a response from the PLC the last time I read from it". The timestamp tells you the last time the PLC responded to the server so you can tell how long communications has been down. Allen Bradley OPC Server Do I need a copy of RS-Linx in order to use this OPC Server? - You do not need RS-Linx or any other third party software in order to use this OPC Server. Once you purchase your IN-GEAR AB OPC Server license you are ready to get to work. For communicating to the Control Logix 5550, do you support native mode tag addressing or the PLC5/SLC500 translated addressing? When you take a Control Logix 5550 CPU out of the box, it is configured to use the Control Logix's tag addressing format that is different from the legacy PLC5/SLC500 file addressing scheme. When the IN-GEAR AB OPC server communicates to the Control Logix 5550 CPU, whether it be by DF1 serial or ethernet via the 1756-Enet module in the PLC, we use the native Control Logix 5550 tag addressing format to communicate to it. If you have configured the mappings in the PLC that let you map PLC5/SLC500 file addresses to the native Logix5550 tags, you will need to use the Logix 5550 native tagnames to read the data using the IN-GEAR AB OPC Server. Can you connect to a ControlLogix through DF-1? Yes, both the AB ActiveX and the AB OPC Server can connect to the ControlLogix or CompactLogix through DF-1. You have to use PLC-5 addressing to do this. All that needs to be done is: a) configure the INGEAR Driver as a Serial DF1 to a PLC-5. b) use the PLC-5 mapping feature of the ControlLogix/CompactLogix to access native tags using PLC-5 addressing. Can you use both channels of a 1784-KTXD card simultaneously with this OPC Server ? Yes you can. The KTXD card is basically two KTX cards on one board that fits into one slot in your PC. You set separate base memory segment addresses for each channel on the card. The AB OPC server talks to the KTXD card using those shared memory segment addresses; therefore to us the KTXD is just two KTX cards to the OPC server. We have tested the server with the KTXD card and know that it can use both channels simultaneously. Do I need a KT card if I want to use this OPC Server? - Not necessarily. The answer to this question is driven by your Allen-Bradley PLC hardware and the network connection you choose, not by this software product. If you are going to connect to your PLC by way of TCP/IP Ethernet or a serial connection then all you need is a standard Ethernet card for an Ethernet connection and a standard RS-232 port for serial DF1 connections. If you are going to connect to your PLC by way of DH+ or DH-485 then you will need some type of hardware interface - which one will depend on your PLC, available PC slots, and future needs. Why is this? The Allen-Bradley Data Highway Plus (DH+) network is Allen-Bradley's twisted pair network - it does not use RS-232 or RS-422/485 -- so in order to interface to it you must use a card in your PC (i.e. a KT, KT-X, KT-Xd, pKT-X, SS-5136, or PCMK or a box that converts from DH+ to a DF1 serial connection (i.e. KF). The same concept applies to DH-485. Although the name, DH-485, implies that you could use an RS-485 port, DH-485 is a token passing network and the protocols used require that some form of hardware interface be used in order to achieve optimum performance. For DH+ and DH-485, the hardware interfaces supported by the IN-GEAR AB OPC server are listed on the product datasheet.