MR52 Two Reader Expansion Module (ADC-AC-MR52) - Installation Guide
Notice: Installation and maintenance servicing for this device should only be performed by qualified personnel.
Note: This article specifically covers the installation of the MR52 Two Reader Expansion Module (ADC-AC-MR52). For instructions on how to set up a broader access system, see Smarter Access Control - Quick Start Guide.
The ADC-AC-MR52 expansion module provides a solution for controlling two additional Wiegand or OSDP readers and door hardware. The ADC-AC-MR52 provides LED control and buzzer control. Six Form-C relay outputs may be used to control locking hardware. Eight inputs are provided that may be used for monitoring the door contact or request-to-exit devices. Input circuits can be configured as unsupervised or supervised using end-of-line resistors. Communication to the Alarm.com Door Controller is accomplished using a 2-wire RS-485 interface. The ADC-AC-MR52 requires 12 to 24 VDC for power. See the following figure for component location.
Wiring
Connections
| TB1-1 | IN1 | Input 1 |
| TB1-2 | ||
| TB1-3 | IN2 | Input 2 |
| TB1-4 | ||
| TB2-1 | IN3 | Input 3 |
| TB2-2 | ||
| TB2-3 | IN4 | Input 4 |
| TB2-4 | ||
| TB3-1 | IN5 | Input 5 |
| TB3-2 | ||
| TB3-3 | IN6 | Input 6 |
| TB3-4 | ||
| TB4-1 | IN7 | Input 7 |
| TB4-2 | ||
| TB4-3 | IN8 | Input 8 |
| TB4-4 | ||
| TB5-1 | TMP | Tamper Input: short = tamper secure |
| TB5-2 | GND | |
| TB5-3 | PFL | Power Failure Monitor |
| TB5-4 | GND | |
| TB6-1 | TR+ | 2-Wire RS-485 Bus |
| TB6-2 | TR- | |
| TB6-3 | NC | Not Used |
| TB6-4 | NC | |
| TB6-5 | GND | Communication Bus Ground |
| TB7-1 | VIN | Input Power |
| TB7-2 | Blank | Not Used |
| TB7-3 | GND | Ground |
| TB8-1 | VO | Reader 1 Power Output |
| TB8-2 | LED | Reader 1 LED Output |
| TB8-3 | BZR | Reader 1 Buzzer Output |
| TB8-4 | CLK/D1 | Reader 1 CLK/D1 |
| TB8-5 | DAT/D0 | Reader 1 CLK/D0 |
| TB8-6 | GND | Reader 1 Ground |
| TB9-1 | VO | Reader 2 Power Output |
| TB9-2 | LED | Reader 2 LED Output |
| TB9-3 | BZR | Reader 2 Buzzer Output |
| TB9-4 | CLK/D1 | Reader 2 CLK/D1 |
| TB9-5 | DAT/D0 | Reader 2 CLK/D0 |
| TB9-6 | GND | Reader 2 Ground |
| TB10-1 | NC | Relay 1 - Normally Closed Contact |
| TB10-2 | C | Relay 1 - Common Contact |
| TB10-3 | NO | Relay 1 - Normally Open Contact |
| TB10-4 | NC | Relay 2 - Normally Closed Contact |
| TB10-5 | C | Relay 2 - Common Contact |
| TB10-6 | NO | Relay 2 - Normally Open Contact |
| TB11-1 | NC | Relay 3 - Normally Closed Contact |
| TB11-2 | C | Relay 3 - Common Contact |
| TB11-3 | NO | Relay 3 - Normally Open Contact |
| TB11-4 | NC | Relay 4 - Normally Closed Contact |
| TB11-5 | C | Relay 4 - Common Contact |
| TB11-6 | NO | Relay 4 - Normally Open Contact |
| TB12-1 | NC | Relay 5 - Normally Closed Contact |
| TB12-2 | C | Relay 5 - Common Contact |
| TB12-3 | NO | Relay 5 - Normally Open Contact |
| TB12-4 | NC | Relay 6 - Normally Closed Contact |
| TB12-5 | C | Relay 6 - Common Contact |
| TB12-6 | NO | Relay 6 - Normally Open Contact |
Jumpers
| Jumper | Description |
|---|---|
| J1 |
Reader Power Select:
|
| J4 | RS-485 Termination, install in last units only |
Wiring an ADC-AC-MR52 for communication and power
If the input voltage to the ADC-AC-MR52 is 12v DC, jumper J1 MUST be in the PT position. Alternatively, if the input voltage to the ADC-AC-MR52 is 24v DC, jumper J1 MUST be in the 12v position to avoid damaging your reader devices as most access control readers have a power input rating of 5-16v DC.
Wiring multiple expansions for communication and power
While the pictured examples show how to wire an ADC-AC-MR52 expansion to a Door Controller (ADC-ACC1-17), LP1501 PoE Door Controller (ADC-AC-LP1501), or LP1502 Door Controller (ADC-AC-LP1502), multiple ADC-ACX1, ADC-AC-MR50, or ADC-AC-MR52 expansion boards may be used as long as you do not exceed eight total expansions per controller.
Additionally, when using multiple expansions you will need to also address them accordingly. For more information, see Which address jumpers need to be installed on the Single Reader Expansion Module (ADC-ACX1)? or Which address DIP switches need to be installed on the ADC-AC-MR52?.
ADC-ACC1-17 / ADC-AC-LP1501
ADC-AC-LP1502
Status LEDs
Power-up:All LEDs OFF. |
Initialization:Once power is applied, initialization of the module begins. When initialization is completed, LEDs A through R2 are briefly sequenced ON then OFF. |
Run time:After a successful initialization, the LEDs have the following meanings:
Every three seconds, LEDs A through R2 are pulsed to their opposite state for 0.1 s. The ADC-AC-MR52 accepts 12 to 24 VDC for power on TB7. Locate the power source as close to the ADC-AC-MR52 as possible. Make power connection with minimum of 18 AWG wires. |
|
Communication wiring
Note: The EOL jumper should be installed at both ends of the communication line. This typically includes the controller and last expansion module.
The ADC-AC-MR52 communicates to an Alarm.com Door Controller using a 2-wire RS-485 interface. The ADC-AC-MR52 allows for multi-drop communication on a bus of up to 4,000 feet (1219 m). Use twisted pair (minimum 24 AWG) with drain wire and shield for communication.
Note: The MR52 RS-485 communication wiring is limited by the host controller's maximum run. For more information about the controller's recommended wire gauge and cable length limitations, see Which wire gauge should be used with Access Control Expansion Modules?.
ADC-ACC1-17 / ADC-AC-LP1501
Up to eight total expansion modules may be wired. The last expansion module on the bus must have jumper J4 installed for ADC-AC-MR52 modules and J1 installed for ADC-AC-MR50 modules.
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ADC-AC-LP1502
Up to sixteen total expansion modules may be wired. The last expansion module on the bus must have jumper J4 installed for ADC-AC-MR52 modules and J1 installed for ADC-AC-MR50 modules.
Use a twisted pair 24 AWG, 120 OHM impedance cable with drain and shield wires. 4,000 ft. (1219 m) maximum total length.
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For ease of install, daisy chain expansion modules together. Wire each expansion module to the next module instead of wiring directly back to the controller.
Install jumpers according to the selected configuration.
Addressing
Flip the DIP switches on the ADC-AC-MR52 expansion module according to the "Jumpers/Switches ON" column in the Access Control Devices table on the Alarm.com Partner Portal. These DIP switches are also displayed in the "Add Expansion Module" installation wizard. If these DIP switches are not set according to the website, the device and its connected readers and door hardware will not function properly with Alarm.com.
Reader wiring
Each reader port supports a single Wiegand or OSDP reader. Power to the reader is selectable: 12 VDC (VIN must be greater than 20 VDC), or power is passed through from the input voltage of the ADC-AC-MR52 (TB7-VIN), 300 mA maximum per reader port. Readers that require different voltages or have high current requirements must be powered separately. 22 AWG minimum recommended for readers.
| 12 V PT | Reader power |
|---|---|
 |
12 VDC is available on reader ports (VIN ≥ 20 VDC) |
 |
VIN power is "passed through" to reader ports |
For more information regarding which position the reader power selection jumper, see When should the Two Reader Expansion Module (ADC-ACX2 or ADC-AC-MR52) be set to use PASS or 12V for the reader power?.
J1 - Reader port power select
If the input voltage to the ADC-AC-MR52 is 12 VDC, jumper J1 MUST be in the PT position.
Reader wiring diagrams
Typical Wiegand reader
Typical OSDP reader
Relay wiring
Six Form-C contact relays are provided for controlling door lock mechanisms. Each relay has a Common pole (C), a Normally Open pole (NO), and a Normally Closed pole (NC). When momentarily delivering power to unlock the locking hardware (fail secure), the Normally Open and Common poles are used. When momentarily removing power to unlock the locking hardware (fail safe), the Normally Closed and Common poles are used. Check with local building codes for proper egress door installation. 18 AWG minimum recommended for electric locking hardware.
Load switching can cause abnormal contact wear and premature contact failure. Switching of inductive loads (strike) also causes EMI (electromagnetic interference), which may interfere with normal operation of other equipment. To minimize premature contact failure and to increase system reliability, a contact protection circuit may be used. The following circuit is recommended. Locate the protection circuit as close to the load as possible (within 12 inches [30 cm]), as the effectiveness of the circuit will decrease if it is located further away.
Typical DC Door Strike wiring
An electrified door strike replaces a traditional door strike for an Access Control system. Door strikes are predominantly Fail-Secure devices, meaning the door remains secure in the event power is removed. This hardware should be wired as Normally Open using an NO terminal as indicated on Fail-Secure wiring diagram above. This is because entry through the door is only granted when the controller is signaled to close the circuit which energizes the strike and allows entry.
Door lock mechanisms can generate EMF feedback to the relay circuit that can cause damage and premature failure of the relay. For this reason, it is recommended that either a diode or MOV (metal oxide varistor) be used to protect the relay. The wire should be of sufficient gauge to avoid voltage loss.
Diode selection
Typical Maglock wiring
An electromagnetic lock or maglock is a is an electromagnet which mounts on a door frame, with a steel armature mounted on the door. Maglocks are Fail-Safe only devices. This means that when power is removed or in the event of a fire alarm input (FAI) signal the maglock unlocks the door as required by code. This hardware should be wired as Normally Closed using an NC terminal as indicated on the Fail-Safe diagram above. This is because constant flowing power is required to keep the maglock energized to secure the door.
MOV selection:
Input wiring
There are 8 inputs that can be used to monitor door position or request to exit devices. Input circuits can be configured as Unsupervised (2 states); reporting as open or closed contact, or Supervised (6 states); reporting as open or closed contact, open circuit, shorted circuit, grounded circuit*, or foreign voltage*.
A supervised input circuit requires adding two resistors with value of 1k ohm, 1% to the circuit to facilitate proper reporting and should be located as close to the sensor as possible.
*Note: Grounded and foreign voltage states are not a requirement of UL 294 and therefore not verified by UL.
The input circuit wiring configurations shown are supported but may not be typical.
22 AWG minimum required for input wiring. 18 AWG recommended if wiring request-to-exit devices in series with locking hardware.
Specifications
The Interface is for use in low voltage, class 2 circuits only.
The installation of this device must comply with all local fire and electrical codes.
Input power
12 to 24 VDC +/- 10%, 550mA max
Output power
12 VDC +/- 10%, 300 mA per reader
Communication
2-Wire RS-485
Inputs
Note: A supervised input circuit requires adding two resistors with value of 1kΩ, 1% to the circuit to facilitate proper reporting and should be located as close to the sensor as possible. For more information, refer to MR52-S3 Reader Interface Installation and Specifications.
Two dedicated reader inputs
Eight programmable inputs
One dedicated tamper input
One dedicated power monitor input
Outputs
Six Form-C relays with dry contacts
Normally open contact (NO): 5 A @ 30 VDC resistive
Normally closed contact (NC): 3 A @ 30 VDC resistive
Certifications
UL 294 recognized
Dimensions (L X W X H )
6.0 x 8.0 x 1.0" (152 x 203 x 25 mm)
Temperature
32°F - 158°F (0°C - 70°C) operational
-67°F - 185°F (-55°C - 85°C) storage
Operating humidity
5-95% (non-condensing) RH
Warranty
Mercury Security warrants the product is free from defects in material and workmanship under normal use and service with proper maintenance for one year from the date of factory shipment. Mercury Security assumes no responsibility for products damaged by improper handling or installation. This warranty is limited to the repair or replacement of the defective unit.
There are no expressed warranties other than set forth herein. Mercury Security does not make, nor intends, nor does it authorize any agent or representative to make any other warranties, or implied warranties, and expressly excludes and disclaims all implied warranties of merchantability or fitness for a particular purpose.
Returns must be accompanied by a Return Material Authorization (RMA) number obtained from customer service, and prepaid postage and insurance.
Liability
The Interface should only be used to control exits from areas where an alternative method for exit is available. This product is not intended for, nor is rated for operation in life-critical control applications. Mercury Security is not liable under any circumstances for loss or damage caused by or partially caused by the misapplication or malfunction of the product. Mercury Security's liability does not extend beyond the purchase price of the product.
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.