# OPC Tags pointing at a single register in an array **URL:** \ **Category:** Ignition\ **Tags:** ignition81\ **Created:** [June 20, 2023, 5:26pm UTC](https://forum.inductiveautomation.com/t/opc-tags-pointing-at-a-single-register-in-an-array/75291 "2023-06-20T17:26:17Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![David\_Murtagh](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@David\_Murtagh](https://forum.inductiveautomation.com/u/David_Murtagh)\ **Post date:** [June 20, 2023, 5:26pm UTC](https://forum.inductiveautomation.com/t/opc-tags-pointing-at-a-single-register-in-an-array/75291/1 "2023-06-20T17:26:17Z")
So I apologize in advance if I get some of the terms wrong. I'm just getting started with OPC and Ignition in general. I am trying to pull ~80 tags from a Mitsubishi PLC. Unfortunately I can't use the new Ignition native driver because I need to read and write from the extended ZR Registers, so I have another OPC solution (Telit DeviceWise, if that matters) that I'm pointing Ignition to. My problem is that I can't seem to pull a single register in Ignition. For example, I want to pull ZR[65008] from the OPC server. I can point an Ignition OPC tag to the ZR memory space and then pull the particular register out with a reference tag but I think that in reality I'm pulling all 65000 tags down when I do that. ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/2/72e83251e9feb09deee6b47da4937ef2ebf69858.png) I want to do something like this to only pull the individual value I'm interested in but I can't seem to get the syntax right. ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/9/b90f8ae4031c4ac17f4e921817701624a684df47.png) I suspect that this is either very simple, or completely impossible. I do have a way to only have the OPC Server publish the specific registers, but that is extremely time consuming and I'd like to avoid it if at all possible. Is there a way to do this in Ignition directly? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [June 20, 2023, 5:28pm UTC](https://forum.inductiveautomation.com/t/opc-tags-pointing-at-a-single-register-in-an-array/75291/2 "2023-06-20T17:28:31Z")
If there is a syntax for this, such as `ZR[65008]`, then it's entirely server specific and something you'll have to refer to their documentation or support to verify. Is that tag you created using that syntax bad quality? ---
**Author:** ![David\_Murtagh](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@David\_Murtagh](https://forum.inductiveautomation.com/u/David_Murtagh)\ **Post date:** [June 20, 2023, 5:37pm UTC](https://forum.inductiveautomation.com/t/opc-tags-pointing-at-a-single-register-in-an-array/75291/3 "2023-06-20T17:37:33Z")
Thanks for the quick response 🙂 The quality of the tag is good and everything else works exactly as expected (binding, scripts, etc). The challenge is that I have ~40 PLCs to connect and I think that this method is pulling down 65000 shorts, so things quickly choke if I try this for more than 1 or 2 PLCs. So it sounds like the syntax for reading data in an OPC tag depends on the OPC UA server (in this case DeviceWise) rather than the client (Ignition). Do I have that correct? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [June 20, 2023, 5:46pm UTC](https://forum.inductiveautomation.com/t/opc-tags-pointing-at-a-single-register-in-an-array/75291/4 "2023-06-20T17:46:34Z")
> [@David\_Murtagh](#): > > So it sounds like the syntax for reading data in an OPC tag depends on the OPC UA server (in this case DeviceWise) rather than the client (Ignition). Do I have that correct? Yes. But while the tag pointing at the whole `ZR` may pull down all the values, I'm not sure why you think the one using `ZR[65008]` is doing the same. ---
**Author:** ![David\_Murtagh](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@David\_Murtagh](https://forum.inductiveautomation.com/u/David_Murtagh)\ **Post date:** [June 20, 2023, 6:16pm UTC](https://forum.inductiveautomation.com/t/opc-tags-pointing-at-a-single-register-in-an-array/75291/5 "2023-06-20T18:16:30Z")
Sorry, I was unclear. I don't think that the Reference tag I'm using to pull out the particular ZR register is pulling all the values. I think the OPC tag I created that the reference tag points to is pulling down all the values. So my UDT has 1 OPC tag that pulls down 65000 values and ~80 reference tags that pull the values out of the OCP tag. The problem is if I create 40+ instances of my UDT I end up with 40+ OPC tags pulling 65000 values each. I run into bottlenecks pretty quick. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [June 20, 2023, 6:23pm UTC](https://forum.inductiveautomation.com/t/opc-tags-pointing-at-a-single-register-in-an-array/75291/6 "2023-06-20T18:23:16Z")
Ooooooh. I totally missed that the tag targeting the array element was a Reference tag and not an OPC tag. Sorry. Yes, you’re right then.