There is an inconsistency between CLI and EDM in release 5.9 which results in an EDM error Wrong Value when select 802.3at and 32w on a port.
See attached solution note from Avaya support webpage.
https://support.avaya.com/ext/index?page=content&id=SOLN320951
This issue was fixed in release 5.10. Upgrading the switch to the latest release should eliminate this error. Upgraded switch to 5.12.3 release. The option in EDM for 802.3at has been removed.
It is possible to set 32w of power on a port configured as 802.3af on the Avaya ERS 4850 as a PWR+ switch supports 802.3at.
If still have issues negotiating power with a PD then try to use LLDP on the PSE and PD.
Below are the power related commands that can be enabled.
Switch(config)Interface ethernet 1/13
Switch(config-if)#lldp status txAndRx config-notification
Switch(config-if)#lldp tx-tlv port 1/13 dot3 mdi-power-support
Switch(config-if)#lldp tx-tlv port 1/13 med med-capabilities
Switch(config-if)#lldp tx-tlv port 1/13 med extendedPSE
The AP must have LLDP enabled also so they can exchange LLDPDUs. This note relates to the experience found providing the power demanded for an Aerohive 650 Access Point on an Avaya ERS 4850GTS-PWR+ switch.