Get-vSphereVersion.ps1

function Get-vSphereVersion(){
    param([string]$servername)

#Ignore certcheck
add-type @"
    using System.Net;
    using System.Security.Cryptography.X509Certificates;
    public class TrustAllCertsPolicy : ICertificatePolicy {
        public bool CheckValidationResult(
            ServicePoint srvPoint, X509Certificate certificate,
            WebRequest request, int certificateProblem) {
            return true;
        }
    }
"@
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy

$Postbody = '<soap:Envelope xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Header><operationID>00000001-00000001</operationID></soap:Header><soap:Body><RetrieveServiceContent xmlns="urn:internalvim25"><_this xsi:type="ManagedObjectReference" type="ServiceInstance">ServiceInstance</_this></RetrieveServiceContent></soap:Body></soap:Envelope>'

$response=irm -Uri https://$servername/sdk -Method POST -Body @($postbody)

return $response.Envelope.Body.RetrieveServiceContentResponse.returnval.about
}