Quartz 4

SSO Binary Input

10 min read

Binary Input Module - Quick Reference SSO

Device Type: Binary Input - Digital Status Monitoring
Signal: Dry contact (NO/NC) or voltage input
Power: 24VAC/VDC (for controller input) or dry contact
Version: 1.0 | Date: Dec 2025

DEVICE OVERVIEW

Common Models:

  • Standalone binary input modules (part of controller), Functional Devices RIB relay with status, Dry contact monitors

Used For:
Proof of operation (fans, pumps, dampers), status monitoring (filter status, flow switches, door contacts), alarm monitoring (fire alarm, freeze stat, high temp), end switches, limit switches

Specifications:

  • Input Types:
    • Dry contact (most common) - voltage-free switch closure
    • Wet contact - voltage present on input
    • Voltage sensing - monitors presence of voltage (24V-277V)
  • Contact Types Monitored:
    • NO (Normally Open) - closes when activated
    • NC (Normally Closed) - opens when activated
  • Wire Type: 18AWG minimum
  • Wiring: 2-wire typical (digital input + common)

Environment: Varies by monitored device

SAFETY - PPE REQUIRED

  • ☑ Safety glasses (ANSI Z87.1)
  • ☑ Work gloves
  • ☑ Insulated gloves if monitoring voltage >50V
  • ☑ Hard hat (if in mechanical room)

HAZARDS

  • ⚠️ VOLTAGE SENSING APPLICATIONS - May involve line voltage (120V-277V)
  • ⚠️ MECHANICAL EQUIPMENT - Monitored devices may have moving parts
  • ⚠️ Warning: Binary input indicates electrical status, not mechanical safety

LOCKOUT/TAGOUT

  • Required if wiring to energized equipment
  • Required if accessing equipment with moving parts
  • NOT required for low-voltage dry contacts
  • Verify voltage type before working

INSTALLATION CHECKLIST

TOOLS NEEDED

  • Wire strippers (18AWG)
  • Screwdrivers
  • Multimeter (DMM)
  • Continuity tester
  • Label maker

MATERIALS

  • Wire (18AWG)
  • Wire nuts or terminal blocks
  • Binary input device (if external module)
  • Status switch/relay (if monitoring equipment without built-in contacts)

PRE-INSTALL

  • Identify device/equipment to monitor
  • Determine contact type available (NO or NC)
  • Verify contact rating if switching current
  • Confirm controller has available binary input point
  • Review wiring diagram

INSTALL STEPS - DRY CONTACT MONITORING

MOST COMMON: Monitoring Auxiliary Contacts

  1. Identify source contacts:

    • Pump/fan starter: Auxiliary contacts (typically NO)
    • Motor starter: Status contacts
    • Relay: Extra contacts if available
    • End switch: Mechanical position switch
    • Flow switch: Paddle or differential pressure switch
    • Pressure switch: High/low pressure cutout
    • Thermostat: Heat/cool status contacts

  2. Determine contact state:

    • NO (Normally Open): Open when off, closes when on
      • Use for: Proof of operation (pump running = closed contact)
    • NC (Normally Closed): Closed when off, opens when on
      • Use for: Alarm monitoring (fire alarm = opens when tripped)

  3. Connect to controller binary input:

    • 2-wire connection (most common):
      • Wire 1: From contact terminal 1 → Controller BI terminal
      • Wire 2: From contact terminal 2 → Controller common
    • Polarity doesn’t matter for dry contacts
    • Tighten terminals: 7-9 in-lbs
    • Route wiring away from high-voltage cables

  4. Configure controller input:

    • Set as NO (normal state = open) or NC (normal state = closed)
    • Example: Motor status NO contact:
      • Motor OFF: Contact open = Binary input FALSE/0
      • Motor ON: Contact closed = Binary input TRUE/1

  5. Label wiring:

    • Example: “PUMP-1-STATUS” or “FILTER-ALARM”
    • Label at both controller and device ends

INSTALL STEPS - VOLTAGE SENSING

For monitoring presence of voltage (line voltage proof):

  1. Select voltage sensing module:

    • Must be rated for monitored voltage (24V, 120V, 208V, 277V)
    • Example: Functional Devices RIBS voltage sensing relay

  2. Connect to monitored circuit:

    • INPUT side (voltage to monitor):
      • Connect voltage sensing module to circuit being monitored
      • Follow module wiring diagram
      • Verify voltage rating before connecting
    • OUTPUT side (dry contacts to controller):
      • Connect module output contacts to controller binary input
      • Typically NO contacts (closed when voltage present)

  3. Configuration:

    • Controller sees dry contact status
    • Voltage present = contact closed = TRUE
    • Voltage absent = contact open = FALSE

POST-INSTALL

  • Wiring connections tight
  • Correct contact type confirmed (NO vs NC)
  • Labels applied at both ends
  • Controller input configured correctly
  • Work area cleaned
  • Photos taken

EXPECTED READINGS

PRE-POWER (Equipment OFF)

Monitoring NO (Normally Open) Contact:

  • Continuity: Open circuit (infinite resistance)
  • Controller Reading: FALSE / 0 / OFF / Inactive

Monitoring NC (Normally Closed) Contact:

  • Continuity: Closed (<1 ohm)
  • Controller Reading: TRUE / 1 / ON / Active

POWER-UP (Equipment ON)

NO Contact (Proof of Operation):

Equipment StateContact StateController Reading
OFFOpenFALSE / 0
ONClosedTRUE / 1

NC Contact (Alarm Monitoring):

Equipment StateContact StateController Reading
NormalClosedTRUE / 1
AlarmOpenFALSE / 0

Controller Configuration:

  • Set controller to expect NO or NC
  • Alarm on Change: Trigger alarm when state changes
  • Alarm on State: Trigger alarm when specific state (TRUE or FALSE)

PROOF OUT TESTS

TEST 1: Contact Continuity Test (Power OFF)

  • Do: Measure continuity across contact with multimeter
  • Expect:
    • NO contact: Open (infinite ohms) when de-energized
    • NC contact: Closed (<1 ohm) when de-energized
  • Pass If: Contact state matches specification

TEST 2: State Change Test

  • Do: Activate equipment (turn pump/fan ON)
  • Expect:
    • NO contact: Changes from open to closed
    • NC contact: Changes from closed to open
    • Controller binary input changes state
  • Pass If: State changes when equipment operates

TEST 3: Manual Contact Test (if accessible)

  • Do: Manually operate contact (close/open by hand if possible)
  • Expect: Controller input responds immediately
  • Pass If: Controller sees state change

TEST 4: Graphics/Controller Display

  • Do: Observe controller graphics or display
  • Expect: Binary input status updates in real-time
  • Pass If: Display matches actual equipment state

TEST 5: Alarm Function Test

  • Do: Trigger alarm condition (if monitoring alarm)
  • Expect: Controller alarm activates
  • Pass If: Alarm notification works correctly

TEST 6: Load Switching Test (if contacts switch power)

  • Do: Verify contact rating adequate for load
  • Measure: Current through contact (if switching power)
  • Pass If: Contact operates without chattering or overheating

TROUBLESHOOTING

BINARY INPUT ALWAYS FALSE (Never TRUE)

  1. Check equipment: Is device actually running?
  2. Test contact: Measure continuity across contact
    • If open when should be closed: Contact not closing - device issue
  3. Check wiring: Verify connections at both ends
  4. Test continuity end-to-end: Should be <5 ohms when closed
  5. Verify controller config: Input set to correct contact type (NO vs NC)?
  6. If wiring OK but no response: Controller input may be failed

BINARY INPUT ALWAYS TRUE (Never FALSE)

  1. Check equipment: Is device actually off?
  2. Test contact: Should be open when equipment off
    • If closed when should be open: Contact stuck - device issue
  3. Check for short circuit: Wires touching somewhere
  4. Verify controller config: May be configured backwards (NO vs NC)
  5. If persistently closed: Contact welded shut or wiring short

BINARY INPUT ERRATIC / CHATTERING

  1. Mechanical chatter: Contact bouncing during switching
    • Solution: Add time delay in controller (0.5-1 sec)
  2. Loose wiring: Check all connections tight
  3. EMI/RFI interference: Route wiring away from power cables
  4. Contact arcing: Contact switching too much current - add relay
  5. Vibration: Secure device and wiring to prevent movement

BINARY INPUT REVERSED (Shows opposite of actual)

  1. Controller config: Input configured as NO when should be NC (or vice versa)
  2. Solution: Change controller configuration to opposite type
  3. Verify logic: Some controllers use “Active High” or “Active Low”

ALARM NOT TRIGGERING

  1. Verify binary input changing state: Check controller display
  2. Check alarm configuration:
    • Alarm enabled?
    • Correct trigger condition (state change vs specific state)?
    • Time delay too long?
  3. Check notification routing: Email, text, or on-screen only?

VOLTAGE SENSING NOT WORKING

  1. Check voltage present: Measure with multimeter at monitored circuit
  2. Verify voltage sensing module powered: Some require separate power
  3. Check voltage rating: Module rated for monitored voltage?
  4. Test module output contacts: Should close when voltage present
  5. If voltage present but module no output: Module failed - replace

ESCALATION - COMPLETE BEFORE CALLING

PRE-ESCALATION CHECKLIST

  • Verified equipment actually operating (visual/audible)
  • Tested contact continuity (open vs closed)
  • Verified all wiring connections tight
  • Tested continuity end-to-end (<5 ohms when closed)
  • Checked controller configuration (NO vs NC)
  • Verified binary input point configured in controller
  • Documented actual equipment state vs controller reading
  • Taken photos of wiring

PROVIDE THIS INFO

  • Monitored Device: [Type / Location]
  • Contact Type: NO / NC / Voltage sensing
  • Equipment State: ON / OFF / Cycling
  • Contact Continuity: Open / Closed / _____ ohms
  • Controller Reading: TRUE/1 / FALSE/0 / Erratic
  • Controller Config: NO / NC / Unknown
  • Symptoms: [Always false, always true, erratic, reversed]
  • Steps Taken: [Troubleshooting completed]

CONTACTS

  • Field Specialist: [Phone]
  • Programmer: [Phone] (if alarm/logic issue)
  • Electrician: [Phone] (if device repair needed)
  • Dispatch: [Phone]

COMMON APPLICATIONS & WIRING

PROOF OF OPERATION (Most Common)

Pump/Fan Status:

  • Source: Auxiliary contacts from motor starter (NO)
  • Wiring: NO contact → Controller BI
  • Logic: Closed when running = TRUE = Equipment ON
  • Alarm: If FALSE for >60 seconds = Failed to start

VFD Run Status:

  • Source: VFD auxiliary relay output (NO)
  • Wiring: Relay NO contact → Controller BI
  • Logic: Closed when VFD running = TRUE
  • Alarm: Command ON but status FALSE = VFD fault

Valve/Damper End Switch:

  • Source: Mechanical limit switch at actuator (NO or NC)
  • Wiring: Switch contact → Controller BI
  • Logic: Closed when fully open (or closed) = TRUE
  • Alarm: Position doesn’t match command = Stuck actuator

ALARM MONITORING

Fire Alarm Interface:

  • Source: Fire alarm panel relay (NC typical)
  • Wiring: NC contact → Controller BI
  • Normal: Closed = TRUE = No alarm
  • Alarm: Opens = FALSE = Fire alarm active
  • Critical: Fail-safe design (wire break = alarm condition)

Freeze Stat (Low Temp Alarm):

  • Source: Capillary tube thermostat (NC)
  • Wiring: NC contact → Controller BI
  • Normal: Closed = TRUE = Temp OK
  • Alarm: Opens = FALSE = Freeze condition
  • Action: Shut down system, notify operator

High Static Pressure Switch:

  • Source: Pressure switch (NC typical)
  • Wiring: NC contact → Controller BI
  • Normal: Closed = TRUE = Pressure normal
  • Alarm: Opens = FALSE = High pressure
  • Action: Shut down fan, check filter

Flow Switch (Proof of Flow):

  • Source: Paddle-type flow switch (NO)
  • Wiring: NO contact → Controller BI
  • Normal (flow): Closed = TRUE = Flow proven
  • Alarm: Open = FALSE = No flow detected
  • Action: Check pump operation, strainer, valves

Smoke Detector:

  • Source: Duct smoke detector relay (NC)
  • Wiring: NC contact → Controller BI
  • Normal: Closed = TRUE = No smoke
  • Alarm: Opens = FALSE = Smoke detected
  • Action: Shut down air handler, activate smoke control

STATUS MONITORING

Filter Differential Pressure Switch:

  • Source: Differential pressure switch (NO)
  • Wiring: NO contact → Controller BI
  • Normal: Open = FALSE = Filter clean
  • Alarm: Closed = TRUE = Filter dirty (high ΔP)
  • Action: Schedule filter change

Water Leak Detector:

  • Source: Water detection sensor (NO)
  • Wiring: NO contact → Controller BI
  • Normal: Open = FALSE = No water
  • Alarm: Closed = TRUE = Water detected
  • Action: Shut down equipment, investigate leak

Door/Window Contact:

  • Source: Magnetic reed switch (NC)
  • Wiring: NC contact → Controller BI
  • Normal: Closed = TRUE = Secure
  • Alarm: Open = FALSE = Door/window open
  • Action: Adjust HVAC for infiltration

WIRING DIAGRAMS

Dry Contact - NO (Normally Open)

Equipment        Controller
Aux Contact      Binary Input
    ┌─┐              ┌────┐
    │ │              │ BI │
NO  │ │──────────────│ 1  │
    │ │              │    │
    │ │──────────────│COM │
    └─┘              └────┘

Dry Contact - NC (Normally Closed)

Equipment        Controller
Aux Contact      Binary Input
    ┌─┐              ┌────┐
    │█│ (closed)     │ BI │
NC  │█│──────────────│ 1  │
    │█│              │    │
    │█│──────────────│COM │
    └─┘              └────┘

Voltage Sensing (Line Voltage)

Line Voltage    Voltage Sensor    Controller
  120VAC         RIBS Module      Binary Input
    ┌──┐            ┌──┐            ┌────┐
HOT │  │───────────│IN│            │    │
    │  │            │  │  NO   ┌───│ BI │
NEU │  │───────────│  │───────┤   │ 1  │
    └──┘            │  │       └───│COM │
                    └──┘            └────┘

COMMON ISSUES & TIPS

✓ NO vs NC confusion: Most common wiring error - verify contact type before wiring
✓ Fail-safe design: Use NC contacts for critical alarms (wire break = alarm)
✓ Fire alarm interface: Always NC contact - must fail to alarm condition
✓ Controller configuration: MUST match actual contact type (NO vs NC)
✓ Contact ratings: Don’t exceed contact amp/voltage rating
✓ Time delays: Add 0.5-1 sec delay to prevent contact bounce false alarms
✓ Wire routing: Keep binary input wiring away from high-voltage to prevent interference
✓ Voltage sensing: Use when no dry contacts available (direct voltage monitoring)
✓ Status feedback: Always verify equipment actually operating (BI shows contact state, not mechanical operation)
✓ Alarm logic: “Alarm on change” vs “Alarm on state” - choose correct
✓ Multiple contacts: Can wire multiple NO contacts in series for “ALL ON” logic
✓ Multiple contacts: Can wire multiple NC contacts in parallel for “ANY ALARM” logic

Document ID: SSO-BINARY-INPUT-001
Revision: 1.0
Next Review: Dec 2026

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