Additional Point Multiplexer Replacement Considerations - Metasys - LIT-12012005 - Field Device - N2 Controller - 13.0

Modernization Guide for N2 Controllers - Metasys

Product name
N2 Controller
Document type
User Guide
Document number
Revision date

Replacement Selection

XMs must be replaced by an N2-capable FEC or CGM; IOMs do not communicate directly on the N2 Bus.

Consider using BO, CO, or UO outputs to replace XM relay outputs. Do the following:

  • Review the electrical characteristics of the load device to ensure compatibility.
  • Ensure the load is compatible with triac or FET output and current limits.

When you replace an XRM module, use Start Stop signal mode of RO outputs of IOM modules.

If using BO or CO outputs instead of XRE/XRL relays, review the electrical characteristics of the load.

  • Load must be compatible with triac output and current limits.
  • For CO outputs in Triac mode, external source jumpers must be in place for each output.

System Involvement

Replacement for any XM points that supported DCM managed systems you can combine them under a single system, managed by an N2-capable FEC or CGM replacing the DCM.

XM points are often tied to control processes through GPL or JCBasic strategies.

  • Search all *.lst files for the supervising NCM to locate XM point involvement.
  • Consider moving the entire control strategy into an N2-capable FEC or CGM device, rather than splitting the process across N2 controllers.

If you plan to reuse the Base Frame Enclosure, for building codes changes, verify that the base-frame enclosure still meets local codes because building codes change.

Base-frame components use dedicated power supplies; a separate 24 VAC power transformer is required for FECs or CGMs. Consider the following:

  • Remove and discard NCU/NEU backplane assembly.
  • Co-located FEC or CGM and IOMs/XPMs can use a common transformer.
  • When calculating power requirements, include all devices powered by a transformer.