Controllogix - limiting tags to external device

[jmalter 1]

Is it possible to limit the tags an extrnal client can read/write in a Controllogix processor? We have a situation where a DCS needs to read and write data to a L71 based system and I would like to protect all other tags from possible manipulation. The DCS vendors preference is to use Ethernet/IP (CIP). We could use a Prosoft card using Modbus and only map what they need however I don't want the extra programming or using a slot.

[Ken Roach 194]

RSLogix 5000 v18 and up has an External Access parameter for every Tag; Read/Write, Read-Only, or None. Updates to RSLinx Classic 2.56 and RSLinx Enterprise 5.21 were required to read Read-Only tags. If it were me, I would put all the HMI interface tags in a specific Program-scope tag database and set them Read/Write. Make everything else everywhere Read-only. I don't think you can designate External Access for specific clients without using FactoryTalk Security. There's a nice thorough description of External Access in RA Knowledgebase Article ID 67071 (TechConnect required). Is this, by any chance, a DeltaV/Mynah interface ? I actually recommended putting in a separate CPU and Ethernet card to a customer, just to serve the Mynah module because the Mynah module will use up all the available ControlLogix communication resources. Edited 2 Aug 2012 by Ken Roach