Danfoss ak cc 550 unable to defrost via digital Input 3

[SIPHON]

Currently I have a danfoss ak cc 550 card controlling a frozen food room, the card is networked with the Danfoss 255 controller panel.

Iam trying to get the cc550 card to initiate defrost via the digital input #3 (DI3) but unable to get the 550 card start a defrost cycle. I have checked the following settings:-
1. Digital input 1 & 2 are used for door alarm and high pressure input shutdown
2.Assigned paramater o84 to function 4
3. Using 240 volt input signal
4 defrost interval and defrost schedules disabled on the 255 controller

Has anyone setup this DI3 or used this function to start defrost.IS there somthing I am missing in the setup?

[joe-ice]

Manual shows the signal for defrost has to be pulsed.apply voltage briefly then remove , a constant 220volt wont work.

[SIPHON]

Have tried pulsing 240v signal but case control still unable to start defrost
Went into status screen on the 255 controller can see digital input #1&2 status when door opens,
but when I put a signal thought digital input 3 it's not changing status?

[joe-ice]

Stumped, have not used di3 before maybe polarity matters, going by other danfoss di modules phase to 23 ,neutral to 22.Is it defrosting normally on its own settings if s5 probe reading high defrost wont start.

[SIPHON]

Solved! The input requires to have a neutral wired into input with 240v signal to initiate defrost
Tested and works.......