To apply N2-capable equipment controllers as replacements for legacy N2 controllers, you need to consider the following:
- Identify how and where the legacy N2 controller is physically mounted and wired.
- Determine if the existing controller enclosure is suitable for the replacement N2-capable equipment controllers by identifying the amount of space available.
- If the replacement
requires the addition of an IOM
or XPM to match point count, additional enclosure space
is required. Be sure that rework of a controller installation conforms to all
local codes. For example, certain models of legacy N2 controllers used spade
lugs connectors; the replacement controllers use screw terminals.
Starting in 2005, the National Electrical Code (NEC) Article 409 mandates specific detail marking in control enclosures. This requirement applies to any enclosures replaced or expanded to hold the CGM, CVM, or FEC family products and accessories.
Input/Output (I/O) profile
Identify the number and types of all input and output devices connected to the legacy N2 controller, these include the signal types required to interface them.
Sequence of operation
Obtain the expected sequence of operation from the legacy N2 controllers. Use one of the following methods:
- Use the legacy N2 controller’s programming tool (HVACPro or GX Tool) to upload the legacy N2 controller’s application file.
- If you are unable to upload the exact file from the target controller, for example, if the controller does not power up, then obtain a saved backup file from the project archives.
- If you are unable to obtain the exact file, then consider uploading a nearby controller with the same or similar application.
- If you are unable to upload or obtain an exact or similar application file, then analyze the mechanical equipment characteristics and control sequence from visual inspection or job documentation and then confirm the expected sequence of operation with the customer.
N2 supervisor integration
Identify which type of N2 supervisor, for example, NCM, N30, Companion, Facilitator, NAE/NCE, SNE/SNC, or FX Supervisory Controller provides supervisory control over the legacy N2 controller. Identify all control features and services, for example, scheduling, optimal start and stop, alarming, trending, interlocking, global data sharing, supervisory code [LCT, GPL, JC Basic], or graphics that the N2 supervisor is applying to the legacy N2 controller.