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Johnson Controls - Metasys M Series  

Air Handling Unit (AHU) Controller

Secondary Control Units
Air Handling Unit (AHU) Controller
Date Last Saved: 1/26/2004 10:59:09 AM

Product Name(s): Air Handling Unit (AHU) Controller
Product Description: The AHU Controller is an application-specific, configurable SCU designed for use with common air handler configurations. The AHU is polled by an NCM (SI) during normal operation and can also operate standalone. It uses pre-programmed air handler control sequences and can be user-modified for custom sequences using 'side loops'.
Product Application(s): The AHU Controller can be used for a variety of specific single-zone, multi-zone, variable air volume, and dual-duct air handler applications requiring up to 16 inputs and 16 outputs.
Point Quantity Characteristics
Analog Input (AI): 8 0-10 Vdc

1000 ohm RTD

4-20 mA

0-25 psig pneumatic with external Function Module Kit

Differential pressure with external Function Module Kit
Digital Input (DI): 8 Dry contact

0-15 Vdc w/2.5V TTL threshold
Universal Input (AI or DI):
Analog Output (AO): 6/See below 4-20 mA (voltage AO requires use of burden resistor)

Pneumatic output with external Function Module Kit
Digital Output (DO): 10 Triac switch (24Vac, 0.5A resistive max)

Optional Line Voltage Relay Kit provides 120/240Vac SPDT relays if required.
Optional Line Voltage Relay Kit provides 120/240Vac SPDT relays if required.
Universal Output (UO):
A/D Converter Resolution
8 bit
10 bit
12 bit
16 bit
D/A Converter Resolution
6 bit
8 bit
10 bit
No Analog Output
HOA switches provided on each output?
Note: These are also available as an add-on from 3rd party vendors.
Both AO and DO
DO Only
Indicating status LED on each output?
AO and DO
AO Only
DO Only
Integral Flow Sensor?
Integral Damper Actuator?
Can controller accept occupant override from thermostat?
Can controller accept occupancy sensor input?
Expander Boards
Network Ports, Protocol(s), and Speed(s) Supported
(Note: See 'Architecture' for network details)
(1) - Proprietary port to secondary 'N2 Network' @ 9.6 kbps (polling)
External Communication Ports, Speeds and Access Devices (1) - EIA-485 port @ 1.2 kbps. To: ZBI.
Additional Information (Optional) Johnson Controls uses the Opto 22 Optomux protocol, which is open and available to developers upon request.
Network Accessing Capabilities via Controller
Access controller only
Access controller plus additional controllers on network segment / LAN
Access all controllers on system
No access available on this controller
Controller Access Devices
Local Display Panel (controller-mounted)
Local Display Panel (zone-mounted)
Handheld Interface Device (proprietary device)
PDA (3rd-Party HID)
Zone-Based port (details below)
Zone-Based Interface Access MetaStat (thermostat with optional RJ-45 zone interface)

Zone Terminal (Handheld Interface that can also be permanently zone-mounted)
Zone Interface Hardware
Zone-Mounted touchpad (thermostat or stand-alone display)
HID (proprietary device)
PDA (3rd party HID, with software)
*Note: This section covers the capabilities for accessing the controller or other parts of the network from the controller (i.e. 'bottom-up').
Standard access functionality is covered in the Architecture and Software sections.
**Does NOT include front-end OI functions. See vendor for specific functions available.
Functions Available Through Field Interface**:View ParamsChange ParamsChange
O&M SupportTAB/Cx Support
Local Display Panel (controller-mounted)
Local Display Panel (zone-mounted)
Handheld Interface Device (proprietary device)
PDA (3rd-Party HID)
Zone-Based port (details below)
Microprocessor(s) 8 bit Intel 8051, operating at 11 MHz
Clock Type
Powered, battery-backed
Battery powered
Powered, no battery backing
Clock Synchronization Clock time on all devices on the N2 network is synchronized daily by the lowest-numbered NCM (SI).
Volatile Memory (RAM) Capacity 32K RAM
Volatile Memory (RAM) Uses
RAM use unrestricted
RAM use restricted as shown below
Information Not Provided
Program Execution / Calculation storage
Data / Trends / Alarms storage
Configuration / Parameter storage
Control Programming storage
Is Volatile Memory Supported By Battery? No
Battery Type(s) N/A
Battery Life N/A
Backup Battery Operating Time N/A
Non-Volatile Memory Capacity (EEPROM/Flash)* 256K Flash Memory

Non-Volatile Memory Uses
Data / Trends / Alarms / Calculation Storage
Configuration / Parameter Storage
Control Programming Storage
Controller Operating System
Additional Information
* Items in NV memory are not lost upon power or battery failure. Other types of NV memory such as EPROM, NOVROM, etc. do not directly impact system performance.
Can trend data be stored in this controller? No
How many total trend values can be stored? Not applicable
What is the controllers role in trending? None. Trend points data is called by the SI (NCM) and stored temporarily before being archived at the OWS
Can controller be programmed to 'push' data to archive or are trends 'pulled' from controller?
When full, does controller automatically send up trend data, overwrite data, or stop logging data? Not applicable
Programming Method(s) Requires HVAC Pro for Windows, a menu-based programming/configuration package. HVAC Pro is run on a laptop or workstation PC, and can be directly connected to the controller via the N2 bus, or via the Zone bus using the Cable Pro EIA-232 (9-pin serial) to EIA-485 (RJ-45) communications interface/adapter. A workstation can be used to run HVAC Pro, with most programming and commissioning features available. Only operating parameters can be modified using PMI User Interface software.
Resident vs Non-Resident Program Execution Standard software is resident in the controller. Custom variations (called 'Side Loops') can be programmed in GPL and reside at the NCM, with commands communicated to the AHU via the N2 secondary network.
Resident/Supervisory. This controller supervises the scheduling of other controllers.
Resident/Stand Alone. This controller contains its own schedule.
Non-Resident. This controller is dependent upon another controller for its schedule.
None. This controller has no scheduling features.
Other The AHU has a 24 hr clock and cannot differentiate between days. If a Zone terminal (ZT) is used, yearly (w/ holiday) scheduling options are available.
Resident Energy Management
Energy management algorithms for this controller can be custom programmed
Pre-programmed/built-in algorithms available, and are fully editable using custom programming
Pre-Programmed/built-in with limited editing via template-based programming
Controller is not typically used for energy management functions
Specific Pre-Programmed Algorithms Available
None (custom programming only)
None (not applicable)
Optimal Start/Optimal Stop
Peak Demand Limiting/Load Shedding
Economizer (enthalpy, dry-bulb, CO2, modulating/2-position, etc.)
Additional Energy Management functions are resident at SI
Additional Programming Functions
DDC Loops (P, PI, PID) PID
Automatic PID Tuning Feature No
Automatical-Dial Alarm Support No
Does controller perform multiple retries and buffer/store alarm until connection is made? No
Are multiple destinations possible? No
Upon controller power loss or hardware failure:
Are network communications affected? No
Is loss recognized on/by the network and alarm reported? Yes. An alarm is generated by the NCM when the controller loses power.
DO and AO response?
Outputs fail to a user pre-specified position
Outputs fail to a normal (unpowered) position
Outputs fail to last position
Volatile memory functions?
Retained for life of backup battery
Upon restoration of power does the controller:
Auto-reboot without operator intervention? Yes
Automatically reset/synchronize the clock? Yes
Update all monitored functions? Yes
Generate an alarm if backup battery is dead? No
Upon network or communications failure does controller:
Continue to operate standalone? Yes
Operate with last global settings or user-specified value? N.A.
Do broken network segments continue to communicate within the remaining segment?
(Note: May depend on proper termination of segments for higher speed networks.)
Does network automatically reconfigure upon restoration? Yes
Does network store 'loss of communications' alarm with time of event? Yes
Additional Information (optional)
Self Test Diagnostics
Does controller have internal self-test diagnostics to check:
Processor failure? Information not provided
Internal hardware failure? Information not provided
Open/shortened sensor? Information not provided
Control Enclosure Multiple enclosure options are available. The AHU board can also be mounted using a DIN rail or direct mount within a field enclosure.
Power Supply Required
Voltage 24 Vac
VA 100 VA
Surge Protection Provided
Underwriters Laboratories UL 916
UL 864
FCC Part 15, Sub-Part B, Class A
LonMark Certified
No - but LonWorks compatible
Information not provided
BACnet (BTL) Certified
Not submitted for testing
Information not provided