Electrify compatible Design Hardware 1000 Series and MARKS USA M9900 Series exit devices with the ACSI 1550K-MDH Motorized Latch Retraction and Dogging Kit.

Designed specifically for these exit-device families, the 1550K-MDH provides quiet 24VDC motorized latch retraction, allowing the exit device to be remotely unlocked through an access-control system, automatic door operator, time schedule, or remote-release circuit.

When energized, the motor retracts the latch while simultaneously depressing the pushbar into the dogged position for controlled free passage.

Key Features

• Genuine ACSI – Architectural Control Systems

• Model 1550K-MDH

• Series 1550K-MD

• Designed specifically for:

  • Design Hardware 1000 Series

  • MARKS USA M9900 Series

• Motorized electric latch retraction

• Simultaneous latch retraction and electric dogging

• 24VDC ±10%

• 1A maximum inrush current

• 400mA maximum holding current

• Continuous-duty rated

• Quiet motorized operation

• Low power consumption

• Non-polarized wiring leads

• On-board diagnostic LEDs

• Automatic retry

• Field-installable kit

• Factory installation available

• Interfaces with access-control systems

• Compatible with automatic door operator applications

• UL listed for compatible panic exit hardware

• UL listed for compatible fire exit hardware

• Exit device sold separately

Compatible Exit Devices

The MDH suffix identifies the ACSI motor-drive kit designed specifically for:

Design Hardware

• 1000 Series

MARKS USA

• M9900 Series

Important

ACSI manufactures multiple 1550K-MD kits for different exit-device manufacturers.

The 1550K-MDH should only be used with compatible Design Hardware 1000 or MARKS USA M9900 Series exit devices.

Motorized Latch Retraction

When 24VDC power is applied, the internal motor retracts the exit-device latch.

This allows the opening to be electronically unlocked without requiring someone to manually depress the pushbar.

Typical control methods include:

• Card readers

• Keypads

• Access-control panels

• Remote release switches

• Time schedules

• Building automation systems

• Automatic door operators

Simultaneous Electric Dogging

The 1550K-MDH provides:

Electric Latch Retraction + Electric Dogging

When energized:

1. The exit-device latch retracts

2. The pushbar depresses

3. The pushbar remains in the dogged position

4. The opening operates in free-passage mode

When power is removed, the exit device returns to its normal mechanical secure condition.

Electrical Requirements

Operating Voltage: 24VDC ±10%

Maximum Inrush Current: 1 Amp

Maximum Holding Current: 400mA

Wiring Leads: Non-Polarized

The kit requires a:

Filtered and Regulated 24VDC Power Supply

Proper power-supply sizing is important for reliable operation.

Continuous-Duty Operation

The 1550K-MDH is:

Continuous-Duty Rated

This allows the exit device to remain electrically retracted for extended authorized unlock periods when connected to a properly sized power supply.

Typical applications include:

• Business-hours unlocking

• Scheduled free passage

• High-traffic entrances

• Access-controlled openings

• Automatic door systems

Quiet Motorized Operation

The motor-drive system provides quieter operation than many traditional high-inrush solenoid latch-retraction systems.

This makes it a good choice for:

• Schools

• Universities

• Hospitals

• Healthcare facilities

• Libraries

• Offices

• Hotels

• Institutional buildings

Automatic Retry

The 1550K-MDH incorporates:

Automatic Retry

If the exit device cannot complete the latch-retraction cycle because of temporary binding or resistance, the system can automatically attempt another retraction cycle.

Diagnostic LEDs

On-board LEDs help installers and service technicians with:

• Installation

• Setup

• Testing

• Troubleshooting

• Operational verification

The diagnostic system can help identify conditions involving:

• Power

• Sensor position

• Failed retraction

• Device binding

• Low voltage

• Motor or control faults

Non-Polarized Leads

The 1550K-MDH uses:

Non-Polarized Wiring Leads

to simplify field wiring.

Device Length Compatibility

ACSI specifies allowable cutoff from the standard exit-device length.

Standard 33" Device

Maximum Allowable Cutoff: 1-1/2"

Standard 42" Device

Maximum Allowable Cutoff: 4-1/4"

Important

Verify the existing device length before ordering.

A device that has already been shortened beyond these limits may not provide enough internal space for the motor-drive assembly.

Recommended Wire Size

For a two-conductor 24VDC circuit, ACSI provides the following general wire-run guidance:

• 70 ft – 22 AWG

• 110 ft – 20 AWG

• 180 ft – 18 AWG

• 280 ft – 16 AWG

• 450 ft – 14 AWG

• 720 ft – 12 AWG

Actual installations should also account for voltage drop and any additional connected loads.

Manual Dogging Removal

If the exit device has an existing manual dogging assembly, the installation procedure calls for removal of those components.

The ACSI motor-drive assembly then provides the:

Electric Dogging Function

Field-Installable Kit

The K designation identifies the 1550K-MDH as a:

Field-Installable Kit

Installation requires access to the exit-device mechanism and pushbar assembly.

Professional installation by a qualified commercial-door or access-control technician is recommended.

Factory Installation Available

The motorized latch-retraction system can also be factory installed when ordering or supplying a compatible exit device through ACSI.

Access-Control Integration

The 1550K-MDH can interface with compatible:

• Access-control panels

• Card readers

• Keypads

• Timers

• Remote release switches

• Building management systems

• Control relays

• Automatic door operators

Automatic Door Operator Applications

The 1550K-MDH works well in properly sequenced automatic-door applications.

A typical operating sequence may be:

1. Access is authorized

2. 1550K-MDH receives 24VDC

3. Exit-device latch retracts

4. Pushbar reaches the dogged position

5. Automatic operator activates

6. Door opens

7. Door completes the operating cycle

8. Exit device returns to secure operation when power is removed

Proper sequencing is important so the operator does not attempt to open the door before the latch is fully retracted.

Panic & Fire Exit Hardware

The ACSI 1550K-MD platform is UL listed for compatible:

• Panic exit hardware

• Fire exit hardware

Important

For fire-rated openings, the complete assembly must maintain its required listing, including:

• Door

• Frame

• Exit device

• Electrification kit

• Power supply

• Wiring

• Control equipment

Always follow applicable life-safety requirements.

Common Applications

Ideal for:

• Access-controlled entrances

• Automatic door systems

• Schools

• Universities

• Hospitals

• Healthcare facilities

• Government facilities

• Retail buildings

• Office buildings

• Institutional facilities

• Scheduled unlock applications

• Remote-release applications

• High-traffic commercial openings

Product Specifications

Brand: ACSI
Manufacturer: Architectural Control Systems, Inc.
Series: 1550K-MD
Model: 1550K-MDH
Product Type: Motorized Latch Retraction / Dogging Kit
Compatible Manufacturers: Design Hardware / MARKS USA
Compatible Series: Design Hardware 1000 / MARKS USA M9900
Voltage: 24VDC ±10%
Maximum Inrush Current: 1A
Maximum Holding Current: 400mA
Duty Rating: Continuous
Operation: Electric Latch Retraction and Dogging
Motorized: Yes
Automatic Retry: Yes
Diagnostic LEDs: Yes
Wiring Leads: Non-Polarized
Field Installable: Yes
Factory Installable: Yes
33" Device Maximum Cutoff: 1-1/2"
42" Device Maximum Cutoff: 4-1/4"
Panic Hardware Listed: Yes
Fire Exit Hardware Listed: Yes
Exit Device Included: No

Compatible Exit Device Series

Design Hardware

• 1000 Series

MARKS USA

• M9900 Series

What's Included

Typical kit includes:

• ACSI motorized latch-retraction assembly

• Device-specific mounting components

• Connecting hardware

• Wiring leads

• Mounting hardware

• Installation components

Exact kit contents may vary with production revisions.

Not Included

• Design Hardware or MARKS USA exit device

• 24VDC power supply

• Power transfer

• Card reader

• Keypad

• Access-control panel

• Automatic door operator

• Control relay

• Field wiring

• Door

• Frame

• Installation labor

Important Ordering Information

Before ordering, verify:

• Exit device is a compatible Design Hardware 1000 Series or MARKS USA M9900 Series

• Exact exit-device configuration

• Device length

• Amount the device has been shortened

• Existing dogging configuration

• 24VDC power-supply capacity

• Wire distance and gauge

• Automatic-operator requirements

• Panic or fire-exit application

Important

1550K-MDH = Design Hardware 1000 / MARKS USA M9900

Do not substitute another ACSI 1550K-MD suffix without confirming exact exit-device compatibility.