To set the user logon hours to 24×7 run the following script:

PS1:

Import-Module ActiveDirectory
$gebruikerslijst = Get-aduser -Filter * -Properties DistinguishedName

Foreach ($gebruiker in $gebruikerslijst){
$user = [ADSI]"LDAP://$gebruiker"
[byte[]]$hours = @(255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255)
$user.logonhours.value = $hours
$user.setinfo() 
}

Each byte represents 8 hours. The first byte start at 1 am at sunday untill 9 am at sunday. This next is byte is from 9 am untill 17 pm at sunday and so forth. Each byte represents of course 8 bit. Each bit is an hour. So to deny access on the first hour one should use 254.

ZIP:

Logonhours