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Wiring a door to a Mercury MP1502

To wire a door to a Mercury MP1502, land the reader on TB1603, door contact and exit button on IN1 and IN2, the maglock on relay 1 NC, and 12–24 V on TB300.

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Applies to Mercury MP1502 · installation guide PLT-07611 rev A.3
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Quick answer

Reader 1 on TB1603, door contact on IN1 (TB1703-3/4), exit button on IN2 (TB1703-1/2), maglock on relay 1 C and NC (TB1800-2/3), 12–24 V DC into TB300-6 and TB300-5.

The steps and the reason are below.

The MP1502 controls two doors. It has two reader ports, eight inputs and four relays, and it runs on 12 to 24 V DC. Each door takes one reader port, two inputs (door contact and exit button) and one relay for the lock. The diagrams below wire door 1 with a Wiegand HID reader, then the same port with OSDP readers.

Which terminals each door uses

The host software decides which input and relay belong to which door. This is the usual layout:

Door Reader Door contact Exit button Lock relay
Door 1 TB1603 IN1 · TB1703-3, -4 IN2 · TB1703-1, -2 Out 1 · TB1800-1, -2, -3
Door 2 TB1601 IN3 · TB1701-3, -4 IN4 · TB1701-1, -2 Out 2 · TB1800-4, -5, -6
Spare IN5 to IN8 · TB1705, TB1707 Out 3 and 4 · TB1802

The spare inputs and relays suit a break-glass monitoring pole, a fire alarm signal or a sounder.

Wire one door with a Wiegand HID reader

The reader takes power from its own port. Everything else that needs power, here the no-touch exit and the lock, runs from the PSU.

MP1502 door 1 wiring: an HID Wiegand reader on reader port 1 (TB1603), the no-touch exit on input 2 and the door contact on input 1 (TB1703), board power, enclosure tamper and PSU fault on TB300, and a fail-safe maglock fed from the PSU through relay 1 normally closed (TB1800) and a break-glass. MP1502 Field devices 12 V PSU READER PORT 1 · TB1603 TB1603-1 · GND TB1603-2 · DAT / D0 TB1603-3 · CLK / D1 TB1603-4 · BZR TB1603-5 · LED TB1603-6 · VO HID READER · WIEGAND Black + drain · 0 V Green · Data 0 White · Data 1 Yellow · beeper Orange · green LED Red · +12 V INPUTS · TB1703 TB1703-1 · IN2 TB1703-2 · IN2 TB1703-3 · IN1 TB1703-4 · IN1 NO-TOUCH EXIT · REX NO +12 V COM 0 V No-touch exit EOL AT BUTTON DOOR CONTACT · DPS COM NC EOL AT CONTACT POWER · TB300 TB300-6 · VIN 12–24 V TB300-5 · GND TB300-4 · TMP TB300-3 · GND TB300-2 · FLT TB300-1 · GND BOARD POWER · 18 AWG PAIR ENCLOSURE TAMPER Switch CLOSED = SECURE PSU FAULT RELAY · CLOSED WHEN OK RELAYS · TB1800 TB1800-1 · NO1 TB1800-2 · C1 TB1800-3 · NC1 TB1800-4 · NO2 TB1800-5 · C2 TB1800-6 · NC2 DOOR 2 +12 V LOCK FEED P1 C P1 NC Break-glass DOUBLE POLE P2 · SPARE, MONITORING + Maglock − 1N4002, CATHODE TO + HOST · J1200 Ethernet · no PoE +12 V 0 V +12 V 0 V Fault Fault +12 V 0 V BATTERY- BACKED FIRE ALARM RELEASE CUTS THIS FEED FUSE +12 V 0 V Contact Lock current Terminal
MP1502 door 1 wiring as a list: each MP1502 terminal and what it connects to, from the reader port to the maglock. READER PORT 1 · TB1603 → HID READER TB1603-1 · GND Black + drain TB1603-2 · D0 Green · Data 0 TB1603-3 · D1 White · Data 1 TB1603-4 · BZR Yellow · beeper TB1603-5 · LED Orange · green LED TB1603-6 · VO Red · +12 V INPUT 2 · TB1703 → NO-TOUCH EXIT BUTTON POWER: PSU +12 V AND 0 V TB1703-1 · IN2 NO TB1703-2 · IN2 COM INPUT 1 · TB1703 → DOOR CONTACT TB1703-3 · IN1 COM TB1703-4 · IN1 NC POWER · TB300 → PSU AND TAMPER TB300-6 · VIN PSU +12 V TB300-5 · GND PSU 0 V TB300-4 · TMP Tamper switch TB300-3 · GND Tamper switch TB300-2 · FLT PSU fault C TB300-1 · GND PSU fault NC RELAY 1 · TB1800 → MAGLOCK FAIL-SAFE: POWER RUNS THROUGH NC TB1800-1 · NO1 not used TB1800-2 · C1 PSU +12 V, fused TB1800-3 · NC1 Break-glass P1 C Break-glass P1 NC Maglock + Maglock − PSU 0 V 1N4002 ACROSS THE LOCK, CATHODE TO + BREAK-GLASS P2: SPARE, FOR MONITORING FIRE RELEASE CUTS THE LOCK FEED HOST · J1200 Ethernet to the network · no PoE
Door 1 on an MP1502: a Wiegand HID reader on TB1603, exit button on IN2, door contact on IN1, and a fail-safe maglock fed by the PSU through relay 1 NC and a break-glass. The dots show data coming in from the reader and current flowing through the lock.

A standard HID pigtail lands like this on reader port 1:

HID wire Signal MP1502 terminal
Black, and the drain Ground TB1603-1 · GND
Green Data 0 TB1603-2 · DAT / D0
White Data 1 TB1603-3 · CLK / D1
Yellow Beeper TB1603-4 · BZR
Orange Green LED TB1603-5 · LED
Red Reader power TB1603-6 · VO
  • Leave the brown (red LED) and blue (hold) wires unconnected unless the reader’s own guide says otherwise. Readers with screw terminals, such as Signo, label them by function: match them the same way.
  • Terminate the drain at the panel end only.
  • Leave J1501 off for a Wiegand reader. It’s the OSDP terminator for reader port 1 (J1502 for port 2).
  • Set the reader port to one-wire LED mode in the host software. In two-wire mode the buzzer output drives a second LED instead of the beeper.
  • Use 6-core 18 AWG cable, up to 152 m.

Power the board, readers and locks

The board takes 12 to 24 V DC on TB300-6 (VIN) and TB300-5 (GND), over at least 18 AWG. It draws up to 500 mA itself, plus up to 600 mA for each reader port: 1.7 A with both ports fully loaded, and 270 mA more with a USB network adapter. Earth the system’s GND in one place only, because a second earth connection invites ground loops.

J503 sets the voltage on the reader ports:

Supply on VIN J503 Reader ports get
24 V 12V (link 1–2) 12 V, regulated
24 V PASS (link 2–3) 24 V
12 V PASS (link 2–3) 12 V

On a 12 V system, set J503 to PASS. The 12V position also passes 12 V through below 14.5 V, but between 14.5 and 17 V it switches reader power off altogether, which a charger running high can trigger. On a 24 V system, PASS puts 24 V on the reader ports, so use it only for readers rated for 24 V.

The board has two more inputs on TB300: TMP for the enclosure tamper switch and FLT for the PSU’s fault relay. Both read a closed contact as normal, so wire them to contacts that are closed when all is well, or fit a wire link across any you don’t use. PSUs label their fault relay differently, so check with a meter which pair is closed while the PSU is healthy.

Wire the maglock fail-safe through relay NC

A maglock locks while it has power, so it runs through the relay’s normally closed contact. Relay 1 sits de-energised and the lock holds. A valid card energises the relay, NC opens and the door releases.

  1. Feed the relay through a fuse PSU +12 V, through a fuse sized for the lock, to TB1800-2 (C1).
  2. Take the lock supply from NC TB1800-3 (NC1) to pole 1 of the break-glass, C side.
  3. Through the break-glass to the lock Break-glass pole 1 NC to the maglock +.
  4. Return to the PSU Maglock − to PSU 0 V.
  5. Protect the relay If the maglock has no built-in suppression, fit an MOV or a diode across it, cathode to +. Mercury sizes the diode for the lock’s current and four times its voltage, so a 1N4002 suits 12 and 24 V locks up to 1 A. A diode slows a maglock’s release slightly; an MOV doesn’t.

The NC contacts are rated 3 A at 30 V DC and the NO contacts 5 A, both resistive. A lock coil is inductive, one more reason for the suppression. A strike that unlocks with power goes on NO and C instead.

Let a dead controller release the door

To have a dead MP1502 release a door whose lock is on the PSU, wire the lock through NO and set the output to energise-to-lock in the host software, if it supports that. The relay then stays energised all day, and the door stays unlocked whenever the board is down or starting up: after every power cut, reboot or fault, and for longer during a firmware update. The board keeps its settings in flash, so it doesn’t wait for the host. It doesn’t replace the break-glass or the fire release.

Supervise the door contact and exit button

Each input can be supervised, so the panel reports a cut or shorted cable as well as open and closed. Supervision needs two 1 kΩ 1% resistors at the device end, as close to the contact as you can get them. Run one twisted pair per input, with no more than 30 Ω in the loop. Without resistors, set the input to unsupervised in the host software. It then reports only open or closed.

Switch the reader port to OSDP

OSDP uses two of the same terminals as Wiegand: TR− on DAT / D0 and TR+ on CLK / D1. BZR and LED aren’t used, because the reader gets its LED and beeper commands over the data pair.

An OSDP reader on MP1502 reader port 1 (TB1603): GND, TR− on DAT/D0 and TR+ on CLK/D1 as a shielded twisted pair, 12 V from VO, BZR and LED unused, jumper J1501 on, and an optional second reader on address 1 daisy-chained at the end of the bus. MP1502 OSDP reader Second reader READER PORT 1 · TB1603 TB1603-1 · GND TB1603-2 · TR− (D0) TB1603-3 · TR+ (D1) TB1603-4 · BZR TB1603-5 · LED TB1603-6 · VO NOT USED ADDRESS 0 GND TR− TR+ +12 V TERMINATOR OFF IF A SECOND READER FOLLOWS SHIELDED TWISTED PAIR ADDRESS 1 · OPTIONAL GND TR− TR+ +12 V END OF BUS: TERMINATOR ON JUMPER J1501 ON · 120 Ω at the panel PORT 2 USES J1502 R1 The dots: the panel polls each reader in turn, and each one answers. R1 on the board flashes every time the panel transmits. POWER VO is 12 V here (J503 sets it), 600 mA for the whole port. A reader that needs more, or another voltage, gets its own supply, with its 0 V joined to GND. CABLE 24 AWG shielded twisted pair, 120 Ω, up to 610 m. Power on its own 18 AWG pair. Drain to GND at the panel only. POLARITY No reply? Swap TR+ and TR−. A reversed pair does no harm. +12 V GND TR− TR+ Optional
An OSDP reader on MP1502 reader port 1 as a list: GND, TR−, TR+ and +12 V, J1501 on, and an optional second reader on address 1. READER PORT 1 · TB1603 → OSDP READER ADDRESS 0 TB1603-1 · GND GND TB1603-2 · TR− TR− TB1603-3 · TR+ TR+ TB1603-4 · BZR not used TB1603-5 · LED not used TB1603-6 · VO +12 V JUMPER J1501 → ON 120 Ω AT THE PANEL · PORT 2 USES J1502 SECOND READER · OPTIONAL ADDRESS 1 · SAME FOUR WIRES FROM READER 1 Reader 1 · GND GND Reader 1 · TR− TR− Reader 1 · TR+ TR+ Reader 1 · +12 V +12 V TERMINATOR ON AT THE LAST READER ONLY CABLE Data: 24 AWG shielded twisted pair, 120 Ω, up to 610 m. Drain to GND at the panel only. Power: a separate 18 AWG pair. VO gives 600 mA for the whole port.
An OSDP reader on reader port 1, with J1501 on and an optional second reader on address 1 at the end of the bus. The dots show the panel polling each reader in turn and each one answering.
  • Termination: fit J1501 (or J1502 for port 2) when the panel is at one end of the bus, and switch on the terminator in the reader at the other end. With two readers, only the last one has its terminator on.
  • Two readers per port at most, on different addresses, for example 0 and 1, at the same baud rate.
  • Cable: one 24 AWG shielded twisted pair, 120 Ω, for data, up to 610 m, plus a separate 18 AWG pair for power. Old Wiegand cores can carry OSDP on short runs, but they may not be twisted pairs, so slow the baud rate down if you reuse them.
  • No reply? Swap TR+ and TR−. Manufacturers disagree on which line is A and which is B, and a reversed pair does no harm.

Set the reader type to OSDP in the host software too. In Avigilon Unity Access I had a reader set to “Custom” that showed green while the panel wasn’t polling it at all. Only with the type set to OSDP did the reader show its real state, and the R1 LED on the board, which flashes as the panel transmits, confirmed the polling.

First power-up

  • A new board, or one after a bulk erase, starts on 192.168.0.251, mask 255.255.0.0, gateway 192.168.0.1.
  • DIP 1 on enables the default login, admin and password, for five minutes. Create your own account straight away. The board reads DIP 1 straight away; the others only at power-up, so reboot after changing them.
  • DIP 4 on makes the board report and behave as an LP1502, for host software that doesn’t know the MP series yet. Leave it on if your host needs it.
  • Put DIP switches 1 to 3 back to off before you hand the site over.

The terminals, ratings, jumpers, DIP switches and LEDs here come from Mercury’s MP1502 Controller Installation and Specifications (PLT-07611, rev A.3, January 2025), which HID support and Mercury’s partners, such as Keri Systems, publish. Check it against the revision that came with your board. The advice on break-glass, fire release, power loss and troubleshooting is general installer practice, not Mercury’s. HID’s support site is support.hidglobal.com.

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