diff --git a/client/components/parameter-list.js b/client/components/parameter-list.js
index d0e1af5..9636851 100644
--- a/client/components/parameter-list.js
+++ b/client/components/parameter-list.js
@@ -2,27 +2,41 @@
 
 import m from "mithril";
 import * as components from "../components";
+import * as store from "../store";
+import * as filterParser from "../../common/filter-parser";
 
 const component = {
+  oninit: vnode => {
+    vnode.state.parameters = Object.values(vnode.attrs.parameters).map(
+      parameter =>
+        Object.assign({}, parameter, {
+          parameter: filterParser.parseParameter(parameter.parameter)
+        })
+    );
+  },
   view: vnode => {
     const device = vnode.attrs.device;
-    const parameters = vnode.attrs.parameters;
-    const filtered = Object.values(parameters).filter(
-      p => p.parameter in device
-    );
-    const rows = filtered.map(p =>
-      m(
-        "tr",
-        m("th", p.label),
+
+    const rows = [];
+    for (let parameter of vnode.state.parameters) {
+      let p = store.evaluateExpression(parameter.parameter, device);
+
+      if (!(p in device)) continue;
+      rows.push(
         m(
-          "td",
+          "tr",
+          m("th", parameter.label),
           m(
-            components.get(p.type || "parameter"),
-            Object.assign({ device: device }, p)
+            "td",
+            m(
+              components.get(parameter.type || "parameter"),
+              Object.assign({}, parameter, { device: device, parameter: p })
+            )
           )
         )
-      )
-    );
+      );
+    }
+
     return m("table.parameter-list", rows);
   }
 };
diff --git a/client/components/parameter-table.js b/client/components/parameter-table.js
index b11fb29..f3d1d4f 100644
--- a/client/components/parameter-table.js
+++ b/client/components/parameter-table.js
@@ -3,12 +3,23 @@
 import m from "mithril";
 import * as components from "../components";
 import * as taskQueue from "../task-queue";
+import * as store from "../store";
+import * as filterParser from "../../common/filter-parser";
 
 const component = {
+  oninit: vnode => {
+    vnode.state.object = filterParser.parseParameter(vnode.attrs.object);
+    vnode.state.parameters = Object.values(vnode.attrs.parameters).map(
+      parameter => {
+        let p = filterParser.parseParameter(parameter.parameter);
+        return Object.assign({}, parameter, { parameter: p });
+      }
+    );
+  },
   view: vnode => {
     const device = vnode.attrs.device;
-    const object = vnode.attrs.object;
-    const parameters = vnode.attrs.parameters;
+    const object = store.evaluateExpression(vnode.state.object, device);
+    const parameters = vnode.state.parameters;
 
     if (!device[object]) return null;
 
@@ -27,17 +38,19 @@ const component = {
 
     const rows = [];
     for (let i of instances) {
-      const row = Object.values(parameters).map(p =>
+      const row = parameters.map(p =>
         m(
           "td",
           m(
             components.get("parameter"),
-            Object.assign({ device: device }, p, {
-              parameter: `${i}.${p.parameter}`
+            Object.assign({}, p, {
+              device: device,
+              parameter: `${i}.${store.evaluateExpression(p.parameter, device)}`
             })
           )
         )
       );
+
       if (device[i].writable === true)
         row.push(
           m(
@@ -90,7 +103,11 @@ const component = {
           )
         )
       );
-    return m("table.table", thead, m("tbody", rows));
+
+    let label;
+    if (vnode.attrs.label) label = m("h2", vnode.attrs.label);
+
+    return [label, m("table.table", thead, m("tbody", rows))];
   }
 };
 
diff --git a/client/components/parameter.js b/client/components/parameter.js
index 7a8e520..0e75687 100644
--- a/client/components/parameter.js
+++ b/client/components/parameter.js
@@ -5,7 +5,9 @@ import * as taskQueue from "../task-queue";
 
 const component = {
   view: vnode => {
-    const param = vnode.attrs.device[vnode.attrs.parameter];
+    const device = vnode.attrs.device;
+    const parameter = vnode.attrs.parameter;
+    const param = device[parameter];
     if (!param || !param.value) return m("span.na", "N/A");
     let value = param.value[0];
     if (param.value[1] === "xsd:dateTime")
@@ -20,10 +22,8 @@ const component = {
           onclick: () => {
             taskQueue.stageSpv({
               name: "setParameterValues",
-              device: vnode.attrs.device["DeviceID.ID"].value[0],
-              parameterValues: [
-                [vnode.attrs.parameter, param.value[0], param.value[1]]
-              ]
+              device: device["DeviceID.ID"].value[0],
+              parameterValues: [[parameter, param.value[0], param.value[1]]]
             });
           }
         },
diff --git a/client/components/summon-button.js b/client/components/summon-button.js
index e814e20..81c2f7f 100644
--- a/client/components/summon-button.js
+++ b/client/components/summon-button.js
@@ -4,20 +4,30 @@ import m from "mithril";
 import * as taskQueue from "../task-queue";
 import * as store from "../store";
 import * as notifications from "../notifications";
+import * as filterParser from "../../common/filter-parser";
 
 const component = {
+  oninit: vnode => {
+    vnode.state.parameters = Object.values(vnode.attrs.parameters).map(
+      parameter => filterParser.parseParameter(parameter)
+    );
+  },
   view: vnode => {
+    const device = vnode.attrs.device;
+
     return m(
       "button.primary",
       {
         title: "Initiate session and refresh basic parameters",
         onclick: e => {
           e.target.disabled = true;
-          const params = Object.values(vnode.attrs.parameters);
+          const params = vnode.state.parameters.map(p =>
+            store.evaluateExpression(p, device)
+          );
           const task = {
             name: "getParameterValues",
             parameterNames: params,
-            device: vnode.attrs.device["DeviceID.ID"].value[0]
+            device: device["DeviceID.ID"].value[0]
           };
 
           taskQueue
diff --git a/client/devices-page.js b/client/devices-page.js
index 354d69d..0bf2109 100644
--- a/client/devices-page.js
+++ b/client/devices-page.js
@@ -12,7 +12,12 @@ import * as components from "./components";
 function init(args) {
   return new Promise(resolve => {
     let filter = new Filter(args.filter);
-    resolve({ filter: filter });
+    let indexParameters = Object.values(config.get("ui.index")).map(p =>
+      Object.assign({}, p, {
+        parameter: filterParser.parseParameter(p.parameter)
+      })
+    );
+    resolve({ filter: filter, indexParameters: indexParameters });
   });
 }
 
@@ -65,7 +70,10 @@ function renderTable(
         },
         m("td", checkbox),
         parameters.map(p => {
-          const attrs = Object.assign({ device: device }, p);
+          const attrs = Object.assign({}, p, {
+            device: device,
+            parameter: store.evaluateExpression(p.parameter, device)
+          });
           const comp = m(components.get(attrs.type || "parameter"), attrs);
           return m("td", comp);
         }),
@@ -156,7 +164,7 @@ const component = {
       }),
       renderTable(
         devs,
-        Object.values(config.get("ui.index")),
+        vnode.attrs.indexParameters,
         count.value,
         selected,
         showMore
diff --git a/client/store.js b/client/store.js
index 76333c5..c9adbf1 100644
--- a/client/store.js
+++ b/client/store.js
@@ -3,10 +3,12 @@
 import m from "mithril";
 import Filter from "../common/filter";
 import * as config from "./config";
+import * as filterParser from "../common/filter-parser";
 
 let fulfillTimestamp = 0;
 
-let unpackedFilters = new WeakMap();
+let unpackedFiltersCache = new WeakMap();
+let expressionsCache = new WeakMap();
 
 const queries = {
   filter: new WeakMap(),
@@ -45,10 +47,10 @@ class QueryResponse {
 }
 
 function unpackFilter(filter) {
-  let f = unpackedFilters.get(filter);
+  let f = unpackedFiltersCache.get(filter);
   if (!f) {
     f = f.evaluateExpressions(fulfillTimestamp);
-    unpackedFilters.set(filter, f);
+    unpackedFiltersCache.set(filter, f);
   }
   return f;
 }
@@ -118,7 +120,9 @@ function fulfill(accessTimestamp, _fulfillTimestamp) {
   let updated = false;
 
   if (_fulfillTimestamp > fulfillTimestamp) {
-    unpackedFilters = new WeakMap();
+    unpackedFiltersCache = new WeakMap();
+    expressionsCache = new WeakMap();
+
     for (let resource of Object.values(resources))
       resource.combinedFilter = null;
     fulfillTimestamp = _fulfillTimestamp;
@@ -366,6 +370,22 @@ function deleteResource(resourceType, id) {
   });
 }
 
+function evaluateExpression(exp, device) {
+  if (!Array.isArray(exp)) return exp;
+
+  let exps = expressionsCache.get(exp);
+  if (!exps) expressionsCache.set(exp, (exps = new WeakMap()));
+
+  if (!exps.has(device)) {
+    let v = filterParser.evaluateExpressions(exp, e => {
+      if (e[0] === "FUNC" && e[1] === "NOW") return fulfillTimestamp;
+    });
+    exps.set(device, v);
+  }
+
+  return exps.get(device);
+}
+
 export {
   count,
   fetch,
@@ -373,5 +393,6 @@ export {
   unpackFilter,
   getTimestamp,
   postTasks,
-  deleteResource
+  deleteResource,
+  evaluateExpression
 };
diff --git a/common/filter-parser.js b/common/filter-parser.js
index 7be373e..3063de3 100644
--- a/common/filter-parser.js
+++ b/common/filter-parser.js
@@ -205,6 +205,36 @@ function parseExpression(exp) {
   return lang.ValueExpression.tryParse(exp);
 }
 
+function evaluateExpressions(ast, funcCallback) {
+  return map(ast, exp => {
+    if (exp[0] === "FUNC") {
+      return funcCallback(exp);
+    } else if (exp[0] === "*") {
+      let v = exp[1];
+      for (let i = 2; i < exp.length; ++i) v *= exp[i];
+      return v;
+    } else if (exp[0] === "/") {
+      let v = exp[1];
+      for (let i = 2; i < exp.length; ++i) v /= exp[i];
+      return v;
+    } else if (exp[0] === "+") {
+      let v = exp[1];
+      for (let i = 2; i < exp.length; ++i) v += exp[i];
+      return v;
+    } else if (exp[0] === "-") {
+      let v = exp[1];
+      for (let i = 2; i < exp.length; ++i) v -= exp[i];
+      return v;
+    } else if (exp[0] === "||") {
+      return exp.slice(1).join("");
+    }
+  });
+}
+
+function parseParameter(p) {
+  return lang.Parameter.tryParse(p);
+}
+
 function stringify(filter) {
   function value(v) {
     if (Array.isArray(v))
@@ -275,5 +305,7 @@ function map(filter, callback) {
 
 exports.parse = parse;
 exports.parseExpression = parseExpression;
+exports.evaluateExpressions = evaluateExpressions;
+exports.parseParameter = parseParameter;
 exports.stringify = stringify;
 exports.map = map;
diff --git a/common/filter.js b/common/filter.js
index c4afc6c..4a25086 100644
--- a/common/filter.js
+++ b/common/filter.js
@@ -67,28 +67,9 @@ class Filter {
 
   evaluateExpressions(now = Date.now()) {
     if (!this.ast) return this;
-    let ast = filterParser.map(this.ast, exp => {
-      if (exp[0] === "FUNC" && exp[1] === "NOW") {
-        return now;
-      } else if (exp[0] === "*") {
-        let v = exp[1];
-        for (let i = 2; i < exp.length; ++i) v *= exp[i];
-        return v;
-      } else if (exp[0] === "/") {
-        let v = exp[1];
-        for (let i = 2; i < exp.length; ++i) v /= exp[i];
-        return v;
-      } else if (exp[0] === "+") {
-        let v = exp[1];
-        for (let i = 2; i < exp.length; ++i) v += exp[i];
-        return v;
-      } else if (exp[0] === "-") {
-        let v = exp[1];
-        for (let i = 2; i < exp.length; ++i) v -= exp[i];
-        return v;
-      } else if (exp[0] === "||") {
-        return exp.slice(1).join("");
-      }
+
+    let ast = filterParser.evaluateExpressions(this.ast, exp => {
+      if (exp[0] === "FUNC" && exp[1] === "NOW") return now;
     });
 
     if (ast === this.ast) return this;
diff --git a/config.json b/config.json
index 780bb8d..c0a7db6 100644
--- a/config.json
+++ b/config.json
@@ -85,6 +85,7 @@
   "ui.device.1.parameters.11.label": "WLAN passphrase",
   "ui.device.1.parameters.11.parameter": "InternetGatewayDevice.LANDevice.1.WLANConfiguration.1.KeyPassphrase",
   "ui.device.2.type": "parameter-table",
+  "ui.device.2.label": "WLAN hosts",
   "ui.device.2.object": "InternetGatewayDevice.LANDevice.1.Hosts.Host",
   "ui.device.2.parameters.1.label": "Host name",
   "ui.device.2.parameters.1.parameter": "HostName",
diff --git a/server/device.js b/server/device.js
index 99470f2..28da8d0 100644
--- a/server/device.js
+++ b/server/device.js
@@ -109,9 +109,9 @@ function recursive(input, root, output, timestamp) {
       childrenTimestamp = input["_timestamp"];
 
     const attrs = {};
-    if (tree["_value"]) {
+    if (tree["_value"] != null) {
       attrs["value"] = [tree["_value"], tree["_type"]];
-      attrs["valueTimestamp"] = childrenTimestamp;
+      attrs["valueTimestamp"] = tree["_timestamp"] || childrenTimestamp;
       attrs["object"] = false;
       attrs["objectTimestamp"] = childrenTimestamp;
     } else if (tree["_object"] != null) {