LP1502 Board Reference

The bulk erase function can be used for the following purposes:

Erase all configuration and cardholder database (sanitize board, less third party applications)
Update OEM default parameters after OEM code has been changed
Recover from database corruption causing LP1502 board to continuously reboot

Do not remove power during steps 1–6.

Set S1: SW1 & SW2 ON, SW3 & SW4 OFF.
Apply power. LED 1 stays on for ~15 seconds while the board boots.
After boot, LEDs 1 & 2 and 3 & 4 alternately flash at a 0.5-second rate.
Within 10 seconds of step 3, change SW1 or SW2 to OFF. If not changed, the board powers up with OEM default communication parameters.
LED 2 flashes while configuration memory is erased (up to 60 seconds). When complete, only LEDs 1 & 4 flash for ~3 seconds.
Board completes initialization 2 seconds after LEDs 1 & 4 stop flashing.

Factory Default Communication Parameters (Interface 1 / NIC1)

Parameter	Value
IP Address	192.168.0.251 (static)
Subnet Mask	255.255.0.0
Default Gateway	192.168.0.1
DNS Server	192.168.0.1
Primary Host Port	IP server · TLS if Available · port 3001 · address 0
Alternate Host Port	Disabled

S1 is a 4-position DIP switch that configures the operating mode of the LP1502 processor. Switches are read on power-up except where noted. X = ON or OFF (don't care). All other switch settings are reserved.

SW1	SW2	SW3	SW4	Definition
OFF	OFF	OFF	OFF	Normal operating mode.
ON	X	X	X	Enables default User Name (admin) and Password (password). Read on the fly — no reboot required.
OFF	ON	X	OFF	Use factory default communication parameters (192.168.0.251).
ON	ON	X	OFF	Bulk Erase prompt mode at power up.
X	X	ON	X	Disables the TLS secure link (read on login only). Not used on LNL-4420 or LNL-X series — TLS is always enabled on those controllers.

In factory or LenelS2 default modes, downloaded configuration/database is not saved to flash memory.

The seven status LEDs on the left edge of the board (D1–D7) indicate board state through individual patterns. D1 and D2 are the primary health indicators; D3–D7 reflect activity on specific subsystems.

D1 — Power / Heartbeat

Pattern	Meaning
Steady ON	Board is powered and booting (first ~15 seconds)
Slow blink (1 s)	Normal operation — processor heartbeat
OFF	No power to board — check TB1 VIN/GND and power supply

D2 — Network / Host Communication

Pattern	Meaning
Steady ON	Ethernet link established, no host communication yet
Rapid blink	Active communication with host software
OFF	No Ethernet link — check cable and switch port at J2

D3 — Reader 1 Activity

Pattern	Meaning
Blinks on card read	Reader 1 (TB8) is receiving Wiegand or Clock-Data
Steady ON	Reader 1 data line held high — possible wiring fault
OFF (no reads)	Normal when no card is presented

D4 — Reader 2 Activity

Same behavior as D3, for Reader 2 on TB9.

D5 — Output / Relay Activity

Pattern	Meaning
ON while relay energized	One or more relays (K1–K4) are active
OFF	All relays de-energized (normal idle state)

D6 — Fault / Alarm

Pattern	Meaning
Steady ON	Active fault condition — tamper, hardware error, or host-defined alarm
Slow blink	Tamper input (TB1 TMP) open — check enclosure tamper loop
OFF	No faults

Boot Sequence Pattern

On a normal power-up: D1 illuminates steady for ~15 seconds, then D1 begins slow blinking. D2 comes on once a network link is detected. D1 & D2 alternating with D3 & D4 at a 0.5-second rate indicates the board is in Bulk Erase prompt mode (see Bulk Erase guide).

LED behavior is firmware-defined. Exact blink rates and fault codes may vary by firmware version. Refer to the LP1502 installation guide or Lenel technical support for version-specific patterns.

TB8 (Reader 1) and TB9 (Reader 2) each accept a 6-conductor reader cable. The terminal layout is identical for both blocks. Both OSDP and Wiegand/Clock-Data reader formats are supported.

OSDP — Terminal Wiring

OSDP (Open Supervised Device Protocol) readers communicate over RS-485. Only two signal wires are needed — BZR and LED are left unconnected as the protocol handles them.

Terminal	Label	OSDP Connection
1	GND	Reader ground and shield drain
2	D0 / DATA	OSDP− (RS-485 A / non-inverting)
3	D1 / CLK	OSDP+ (RS-485 B / inverting)
6	VO	Reader power — set J7 for correct voltage

OSDP+ and OSDP− labeling varies by reader manufacturer. If the reader does not communicate after wiring, swap D0 and D1 — RS-485 polarity is the most common cause of a silent OSDP reader.

OSDP — Enabling in OnGuard

OSDP mode must be configured in Lenel OnGuard System Administration for each reader port that uses an OSDP reader:

In System Administration, open the panel and navigate to the reader configuration for Reader 1 or Reader 2.
Set the Reader Type to OSDP.
Set the OSDP Address to match the address configured on the reader (default is typically 0).
Set the Baud Rate to match the reader (typically 9600 or 115200 — check the reader's data sheet).
Download the configuration to the board and verify the reader LED responds via OSDP feedback.

OSDP provides bi-directional communication, enabling features not available with Wiegand: tamper detection, reader status feedback, encrypted credential transmission (OSDP v2 Secure Channel), and remote LED/buzzer control without separate wires. Verify your reader and firmware version both support the OSDP v2 feature set if Secure Channel is required.

Wiegand / Clock-Data — Terminal Wiring

Wiegand and Clock-Data readers use all six conductors. Wire colors are typical but not standardized — always verify against the reader's installation sheet.

Terminal	Label	Typical Wire Color	Function
1	GND	Black	Reader ground and shield drain
2	D0 / DATA	Green	Wiegand D0 — or Clock-Data DATA line
3	D1 / CLK	White	Wiegand D1 — or Clock-Data CLOCK line
4	BZR	Orange	Buzzer control output (open drain, max 50 mA)
5	LED	Brown / Blue	LED control output (open drain, max 50 mA)
6	VO	Red	Reader power — voltage set by J7

Cable Requirements — Wiegand vs. OSDP

Spec	Wiegand / Clock-Data	OSDP
Cable type	22 AWG 6-conductor shielded (e.g., Belden 9536)	22 AWG 4-conductor shielded twisted pair
Max run length	500 ft (152 m)	4,000 ft (1,200 m)
Shield grounding	Panel end only	Panel end only
Termination	Not required	120 Ω across D0/D1 at far end for runs over ~50 ft

Shield Grounding (Wiegand & OSDP)

Connect the cable shield drain wire to the GND terminal (Terminal 1) at the panel end only. Leave the shield floating or insulated at the reader end. Grounding at both ends creates a ground loop that causes intermittent read errors.

Reader Power Voltage (Wiegand & OSDP)

Set jumper J7 to match the reader's supply voltage requirement before powering up. Most modern proximity and smart card readers require 12V. Applying the wrong voltage will damage the reader. See the Reader Power Voltage Select guide for J7 positions.

Inputs IN1–IN8 (terminal blocks TB4–TB7) support 4-state supervision using end-of-line (EOL) resistors. Supervision allows the panel to detect four distinct states on a single loop, providing tamper detection that a simple dry contact cannot.

4-State Supervision — Standard Resistor Values

State	Loop Resistance	Typical Cause
Normal (secured)	~1,000 Ω	Door closed, contact closed, 1 kΩ EOL in series
Alarm (unsecured)	~2,000 Ω	Door open, contact open, 1 kΩ + 2 kΩ across loop
Short (tamper)	< 100 Ω	Wire shorted — possible tampering or fault
Open (cut/fault)	> 10,000 Ω	Wire cut or contact failed open without resistor path

Wiring Diagram (4-State)

Place the 1 kΩ resistor in series with the normally-closed contact. Place the 2 kΩ resistor in parallel across the contact terminals (bridging the contact). Both resistors should be installed at the device end of the cable, inside the protected device's housing.

Run two conductors from the input terminal block to the door contact.
At the contact, wire one resistor (1 kΩ) in series with the NC contact loop.
Wire the second resistor (2 kΩ) in parallel directly across the contact terminals.
Return the loop wires to the panel input terminal and GND.

Dry-Contact (Unsupervised) Wiring

For non-supervised inputs, wire the dry contact directly between the input terminal and GND with no resistors. Configure the input type in OnGuard as "Unsupervised" to avoid false tamper alarms.

Each input terminal block on this board provides one wire terminal per input channel — GND is shared. Confirm the GND terminal assignment in your specific firmware documentation if inputs behave unexpectedly.

Relays K1–K4 are wired through TB10 (K1/K2) and TB11 (K3/K4). Each relay provides three terminals: C (common), NO (normally open), and NC (normally closed). Use the appropriate terminals based on the lock type and fail-safe requirement.

Fail-Safe Magnetic Lock (power to lock)

Magnetic locks hold the door secure when powered and release when power is removed. Wire between C and NO. The relay energizes to unlock (apply power to lock coil) — the door is locked when power is present and unlocked on relay energize.

This is counter-intuitive: in software, "Access Granted" energizes the relay, which closes the NO contact, which cuts power to the mag lock, releasing the door. Verify output point logic in OnGuard matches this behavior.

Fail-Secure Electric Strike (power to unlock)

Electric strikes remain locked (latched) when de-powered and unlock when power is applied. Wire between C and NO. The relay energizes to apply power to the strike, which releases the latch. On power failure, the strike stays locked.

Monitoring NC Contact

The NC terminal can be used to monitor relay state or provide an interlock. When the relay is de-energized, NC is closed. When energized, NC opens. Some installations use this for relay health monitoring back to the access control system.

Relay Contact Ratings

Spec	Value
Max current	1 A
Max voltage	30 VAC or 30 VDC
Load type	Resistive or inductive (with suppression)

Inductive Load Suppression

Magnetic locks and electric strikes are inductive loads. When switched off, they produce a voltage spike that can damage relay contacts over time. Install a flyback diode (1N4001 or equivalent) across the lock terminals at the lock end, oriented to clamp the reverse spike. For AC-powered locks, use a MOV or RC snubber instead of a diode.

Do not exceed relay contact ratings. For loads greater than 1 A or voltages above 30V, use the relay to switch a separate interposing relay or solid-state relay sized for the actual load.

The LP1502 ships configured for DHCP. For most installations, a DHCP reservation is the recommended approach — it gives the board a stable IP without requiring static configuration on the board itself.

Option A — DHCP Reservation (Recommended)

Connect the board to your network via J2 (RJ-45).
Power on the board and wait for D1 to begin slow blinking (~15 seconds).
Find the board's MAC address on the label on the board itself.
In your DHCP server (router or Windows DHCP), create a reservation binding that MAC address to a fixed IP.
Reboot the board (press S2 momentarily or cycle power). It will acquire the reserved IP.
Verify connectivity by pinging the reserved IP from a PC on the same subnet.

Option B — Static IP via Web Browser

Set your PC to a static IP on the 192.168.0.x subnet (e.g., 192.168.0.100 / 255.255.0.0).
Connect a straight-through Cat5e/6 cable from your PC directly to J2, or put both on the same switch.
Open a browser and navigate to http://192.168.0.251 (factory default IP).
Log in with username admin / password password (set S1 SW1 ON first if credentials have been changed).
Navigate to Network Settings and configure the desired static IP, subnet mask, gateway, and DNS.
Save and reboot. Reconnect using the new IP.

Factory Default Network Parameters

Parameter	Value
IP Address	192.168.0.251 (static)
Subnet Mask	255.255.0.0
Default Gateway	192.168.0.1
DNS Server	192.168.0.1

Connecting to OnGuard

Once the board has a reachable IP, add it as a panel in Lenel OnGuard System Administration using the board's IP address and port 3001. Ensure the host server's firewall allows outbound connections on port 3001, or that the board can reach the server on the configured host port.

If the board cannot reach the host software, verify that no firewall or VLAN is blocking TCP port 3001 between the board's IP and the OnGuard server's IP.

TB3 provides the RS-485 serial connection to the host panel or communication server. RS-485 is a multi-drop bus — multiple LP1502 boards can be daisy-chained on a single cable run.

TB3 Terminal Assignment

Terminal	Label	Function
1	TR+	RS-485 Positive
2	TR−	RS-485 Negative
3	GND	Signal Ground

Topology Rules

Daisy-chain only. Run one continuous cable from the host to each board in series. Do not use star or T-tap wiring — stubs cause reflections that corrupt data.
Terminate at both endpoints only. Install the 120 Ω terminator (J5 jumper installed) at the host end and at the last board on the run. Remove J5 from all mid-run boards. Do not enable both J5 and S1 SW4 on the same board simultaneously.
Ground at one end only. Connect the cable shield to earth ground at the host panel end. Leave the shield floating at the board end. Grounding at both ends creates a ground loop.

Cable Specifications

Spec	Value
Cable type	Belden 9842 or equivalent — 22 AWG shielded twisted pair
Max run length	4,000 ft (1,200 m)
Max devices per run	32 unit loads (typically 16–31 boards depending on transceiver)
Typical baud rate	19,200 bps (configurable in OnGuard)

Longer runs at higher baud rates are more sensitive to termination and cable quality. If experiencing intermittent communication errors, verify termination is installed only at the two true endpoints and check for any T-taps or parallel stubs in the run.

BT1 is a BR2330 or CR2330 3V lithium coin cell that keeps the real-time clock (RTC) running during power outages. A dead battery causes the clock to reset to a default date/time on every power cycle, producing incorrect event timestamps in OnGuard.

When to Replace

Indicator	Action
Event timestamps reset to Jan 1 after any power loss	Replace BT1 immediately
Board age > 3–5 years in service	Replace proactively
Routine annual inspection (mission-critical sites)	Replace regardless of voltage

Replacement Procedure

Verify J19 is installed (battery backup enabled). If not, install it before starting.
The board does not need to be powered off for battery replacement — the RTC will maintain time from the power supply while you swap. Schedule replacement during low-activity hours as a precaution.
Locate BT1 — the large silver coin cell in the center-left area of the board.
Use a non-conductive spudger or plastic pry tool to gently slide or pop the battery out of its holder. Do not use metal tools that could short adjacent components.
Insert the replacement battery positive (+) side up (the flat, labeled face). Press firmly until it seats.
Verify the board resumes normal operation (D1 heartbeat blink). Check OnGuard for correct time on the next event.

Replacement Part

Spec	Value
Part number	BR2330 or CR2330
Voltage	3V lithium
Diameter × Height	23 mm × 3.0 mm
Expected standby life	3–5 years

Remove J19 when storing or shipping boards for extended periods to prevent battery drain from the idle RTC circuit. Re-install J19 before deployment.

The LP1502 can receive firmware updates via a microSD card inserted into J8. This method is used when the board cannot reach the host server, or when Lenel provides a standalone firmware image for field update.

Only install firmware provided by Lenel S2 or TRL Systems. Installing incorrect or corrupted firmware can render the board unresponsive and may require a factory recovery procedure.

microSD Card Requirements

Spec	Requirement
Type	microSD or microSDHC
Capacity	Up to 32 GB
Format	FAT32
Speed class	Class 4 minimum; Class 10 recommended

Update Procedure

Format the microSD card as FAT32 on a PC.
Copy the firmware image file provided by Lenel to the root directory of the card. Do not place it in a subfolder.
Power down the LP1502 (remove power from TB1).
Insert the card into J8 (slot on the right side of the board). The card clicks into place — do not force it.
Apply power. The board will detect the firmware image on startup and begin the update process. D1–D7 may display a specific blink pattern during the update (refer to the release notes for the pattern).
Wait for the update to complete — typically 2–5 minutes. Do not remove power or the card during this time.
The board will reboot automatically when the update is finished. D1 will resume its normal heartbeat blink.
Power down, remove the microSD card, and power back up for normal operation.

After a firmware update, verify the board reconnects to OnGuard and that all door, reader, and input programming is intact. In rare cases a firmware update may reset communication parameters — have the board's IP and host settings recorded before updating.