diff --git a/lib/config.coffee b/lib/config.coffee
index 377da1e..3b255c5 100644
--- a/lib/config.coffee
+++ b/lib/config.coffee
@@ -65,6 +65,7 @@ options = {
   LOG_FORMAT : {type : 'string', default : 'simple'},
   ACCESS_LOG_FORMAT : {type : 'string', default : ''},
   MAX_CONCURRENT_REQUESTS : {type : 'int', default: 20},
+  DATETIME_MILLISECONDS : {type: 'bool', default: true},
 
   # XML configuration
   XML_RECOVER : {type : 'bool', default : false},
diff --git a/lib/device.js b/lib/device.js
index cc5ff40..0e0904e 100644
--- a/lib/device.js
+++ b/lib/device.js
@@ -66,7 +66,8 @@ function sanitizeParameterValue(parameterValue) {
         break;
       case 'xsd:dateTime':
         if (typeof parameterValue[0] !== 'number') {
-          let v = parseInt(parameterValue[0]);
+          // Don't use parseInt because it reads date string as a number
+          let v = +parameterValue[0];
           if (isNaN(v)) {
             v = Date.parse(parameterValue[0]);
             if (isNaN(v))
diff --git a/lib/session.coffee b/lib/session.coffee
index 7c05c6b..b6974de 100644
--- a/lib/session.coffee
+++ b/lib/session.coffee
@@ -1013,25 +1013,31 @@ generateSetRpcRequest = (sessionContext) ->
 
   # Set values
   GPV_BATCH_SIZE = config.get('GPV_BATCH_SIZE', sessionContext.deviceId)
+  DATETIME_MILLISECONDS = config.get('DATETIME_MILLISECONDS', sessionContext.deviceId)
 
   parameterValues = []
   syncState.spv.forEach((v, k) ->
     return if parameterValues.length >= GPV_BATCH_SIZE
+    syncState.spv.delete(k)
     attrs = sessionContext.deviceData.attributes.get(k)
     if (curVal = attrs.value?[1])? and attrs.writable?[1]
       val = v.slice()
       val[1] = curVal[1] if not val[1]?
       device.sanitizeParameterValue(val)
 
+      # Strip milliseconds
+      if val[1] == 'xsd:dateTime' and not DATETIME_MILLISECONDS and typeof val[0] == 'number'
+        val[0] -= val[0] % 1000
+
       if val[0] != curVal[0] or val[1] != curVal[1]
         parameterValues.push([k, val[0], val[1]])
-        syncState.spv.delete(k)
   )
 
   if parameterValues.length
     return {
       name: 'SetParameterValues'
       parameterList: ([p[0].join('.'), p[1], p[2]] for p in parameterValues)
+      DATETIME_MILLISECONDS: DATETIME_MILLISECONDS
     }
 
   # Download
diff --git a/lib/soap.js b/lib/soap.js
index 08e6b67..cfc359c 100644
--- a/lib/soap.js
+++ b/lib/soap.js
@@ -210,10 +210,13 @@ function SetParameterValues(xml, methodRequest) {
   for (const p of methodRequest.parameterList) {
     const pvs = paramList.node("ParameterValueStruct");
     pvs.node("Name").text(p[0]);
-    if (p[2] === 'xsd:dateTime' && Number.isInteger(p[1]))
-      pvs.node("Value").attr({"xsi:type": p[2]}).text((new Date(p[1])).toISOString());
-    else
-      pvs.node("Value").attr({"xsi:type": p[2]}).text(p[1]);
+    let val = p[1];
+    if (p[2] === 'xsd:dateTime' && typeof val === 'number') {
+      val = (new Date(val)).toISOString();
+      if (methodRequest.DATETIME_MILLISECONDS === false)
+        val = val.replace('.000', '');
+    }
+    pvs.node("Value").attr({"xsi:type": p[2]}).text(val);
   }
 
   el.node("ParameterKey").text(methodRequest.parameterKey || "");