Match LP1502 reader power selection to the input supply

Bottom line: DSE recommends reviewing the LP1502 input supply and reader-power selection together. Have qualified personnel compare the actual supply, J7 position and reader requirements with the exact manual before deciding that a reader-power problem calls for another component or configuration change.

Source fact: the manual pairs input and jumper selection

Section 2.7 of the LP1502 installation manual, PLT-05244 revision A.7, requires J7 in PASS when the controller input is 12 V DC. The adjacent table shows 0 V reader output for the combination of 12 V input and the 12 V reader-power selection.

The same section specifies a maximum of 300 mA per reader port. It directs readers with different voltage or high-current requirements to separate power. These are LP1502 A.7 manual details; they are not limits or jumper instructions for every Mercury controller.

What the source does not establish

The table does not size a complete installation power supply, certify a particular reader/controller pairing or authorize work on energized equipment. It also does not establish the requirements of an unidentified reader. Use the exact controller and reader documentation, approved drawings and qualified installation procedure for the intended work.

Applicability questions

• Is the board an LP1502 covered by this manual revision?
• What supply is actually connected, and where is that identity recorded?
• Which reader-power selection is installed on J7?
• What voltage and current requirements does the exact reader documentation state?
• Who is authorized to inspect, measure or change the installation under the approved procedure?

DSE recommendation: review the complete pairing

The following steps are DSE recommendations based on the manual’s power-selection boundaries.

Prepare a concise record of the controller, supply and reader identities. Include the relevant manual revision and drawing reference. Ask the responsible installer to reconcile the documented input supply and jumper selection before ordering a replacement reader or changing unrelated access-control settings.

Compare the proposed reader connection with the reader’s documented requirements. Have the designer identify whether controller-supplied power is appropriate for that specific configuration or whether a separate supply is required. Keep that decision explicit; do not interpret a familiar connector or a jumper label as a substitute for the reviewed combination.

Arrange any inspection or measurement through qualified personnel using the approved isolation and work procedure. Preserve the prior configuration and define the permitted change, acceptance condition and recovery contact. This article is a review aid, not an instruction to move a jumper during live operation.

Verification and evidence

For an approved installation or diagnostic task, have the responsible technician record the observed input, selected jumper position and reader supply result using the authorized method. Compare that record with the applicable manual table and the intended reader requirements.

After the electrical review is complete, perform the separately agreed access workflow check with the opening’s owner. Keep the power observation distinct from credential acceptance, controller communication and the physical door result. Investigate an unresolved discrepancy at its own stage rather than replacing several components together.

Retain the exact equipment identities, manual pages, approved drawing, authorized observations and final configuration. Require the same comparison when a reader or supply is substituted so the earlier acceptance does not silently extend to a different combination.

Official references

• LP1502 Controller Installation and Specifications — Mercury; PLT-05244 revision A.7, February 2026; sections 2.1.1 and 2.7, pages 8 and 12.

Source review completed October 28, 2026. Recheck the official documentation and deployment-specific applicability before a production change.