A Digi One IAP that remains off on a Cisco 3560-24PS is not proven defective merely because an IP phone powers from the same port. The available hardware evidence identifies a compatibility problem: the original Digi One IAP PoE implementation supports power on the unused Ethernet pairs only, while the switch may deliver power on the active data pairs. Conflicting injector results also require testing the exact device and injector combination before deployment.
Identify the PoE compatibility boundary
The original Digi One IAP hardware supports only the unused-pair method, described in the evidence as midspan. It does not support the active-pair method described as end-span. Full 802.3af operation requires a powered device to accept either conductor set, so this hardware must not be treated as fully 802.3af compliant.
| Power method | Conductors stated in the evidence | Original Digi One IAP support |
|---|---|---|
| Unused-pair / midspan | Positive on pins 4 and 5; ground on pins 7 and 8 | Supported method |
| Active-pair / end-span | Power on pins 1 and 2; ground on pins 3 and 6 | Not supported |
A bench test reportedly powered one unit with 48 V on pins 4 and 5 and ground on pins 7 and 8. That result demonstrates operation for that unit and wiring arrangement; it does not establish compliant detection, polarity handling, or compatibility with every injector.
Interpret the Cisco 3560-24PS symptom correctly
The working IP phone confirms that the tested switch port can power that phone. It does not prove that the port presents power on the conductor set required by the Digi One IAP. The evidence reports that the Cisco port may default to end-span delivery, whereas the original IAP requires midspan delivery.
One account says Cisco Support supplied commands that changed a switch from end-span to midspan, but the commands were not recorded. Treat switch-side selection as an unverified possibility, not a documented configuration procedure. Confirm available power modes through current Cisco documentation or an official support channel for the exact switch configuration.
Account for conflicting injector results
The field reports are inconsistent: one installation powered 21 Digi devices successfully from a standalone 3Com PoE unit, and another update says purchased midspan injectors solved the problem. A separate final report says a Digi One IAP did not operate from a PoE injector. The evidence does not identify the injector models, IAP hardware revisions, wiring, polarity, detection behavior, or measured voltage for the failed combination.
Therefore, “midspan injector” is a necessary compatibility description for the original hardware, but it is not sufficient proof that an unspecified injector will work. Do not select an injector solely from the result of an IP-phone test or from its marketing label.
Run a controlled compatibility test
- Identify the exact Digi One IAP hardware revision and confirm whether it is the original midspan-only design or a later product variant. Product names and model numbers for the proposed full-compliance hardware were not established in the evidence.
- Determine which conductor set the Cisco 3560-24PS is actually energizing for this connection. Do not infer the mode from successful operation of the Cisco 960G phone cited in the report.
- If the switch supplies only the active pairs, test with a known midspan source that applies power to pins 4 and 5 with the return on pins 7 and 8. Use documented equipment rather than an unverified DIY injector circuit.
- Confirm that the IAP starts, establishes its Ethernet link, and continues operating under the intended network and serial load.
- If it still does not start, record the IAP revision, injector model, conductor assignment, polarity, and measured input voltage, then escalate the compatibility case through official manufacturer support.
Verify the deployment result
Accept the installation only after the exact production combination powers repeatedly and maintains communications. Verify cold startup, Ethernet link, and the required serial-to-network transaction. A lit phone, an injector label, or an unloaded voltage measurement alone does not verify IAP compatibility.
For replacement planning, note that the evidence describes a future Digi design intended to support both midspan and end-span power, while standard Digi One IAP hardware was expected to lose PoE in favor of a separate PoE-capable product. Because exact names, model numbers, prices, and release status were uncertain, verify the current ordering code and PoE specification before substitution.
FAQ
Why does a Digi One IAP not power from a Cisco 3560-24PS?
The original IAP supports unused-pair midspan power, while the switch may supply active-pair end-span power. A phone working on the same port does not prove conductor-set compatibility.
Which Ethernet pins power the original Digi One IAP?
The reported working midspan arrangement applies 48 V to pins 4 and 5 with ground on pins 7 and 8. Confirm polarity and source behavior for the exact hardware before connection.
Will any midspan PoE injector power a Digi One IAP?
No universal result is supported: some reported midspan installations worked, while another injector test failed. Validate the exact injector, IAP revision, wiring, voltage, startup, and communications together.