title: OpenHAB2 access to MODBUS RTU slave device
body: <p>Running OpenHab2 on my Windows10, I am not able to get OpenHAB2 to request holding register data from the serial port. No MODBUS request are seen on the port.
  I installed  NTP-binding (ntp time) (it works), and tried the Modbus binding 1.12.0, seems though only valid for OpenHAB1.</p>
  
  <p>My OpenHAB2 configuration is</p>
  
  <p>.sitemap</p>
  
  <pre><code>    sitemap boiler label="My home" 
      {
          Frame label="Date" 
          {
            Text item=Date
            Text item=holding1501 label="Holding1501 out[%.1f °C]"
            Text item=holding1500 label="Holding1500 out[%.1f °C]"
          }
      }
  </code></pre>
  
  <p>.items</p>
  
  <pre><code>    DateTime Date  "Date [%1$tA, %1$td.%1$tm.%1$tY %1$tH:%1$tM:%1$tS]"  { channel="ntp:ntp:local:dateTime" }
      Number holding1501 "Holding1501 [%.1f]" &lt;temperature&gt; {channel="modbus:data:localSerial:holding:holding1501:number"}
      Number holding1500 "Holding1500 [%.1f]" &lt;temperature&gt; {channel="modbus:data:localSerial:holding:holding1500:number"}
  </code></pre>
  
  <p>and  .things</p>
  
  <pre><code>    Bridge modbus:serial:localSerial [port="COM6", id=10, baud=19200, stopBits="1", parity="even", dataBits=8, encoding="rtu"]
      {
          Bridge poller holding [ start=1500, length=1, refresh=1000, type="holding" ] 
          {
              Thing data holding1500 [ readStart="1500", readValueType="int16", writeStart="1500", writeValueType="int16", writeType="holding" ]
              Thing data holding15011 [ readStart="1501", readValueType="int16", writeStart="1501", writeValueType="int16", writeType="holding" ] 
          }
          Thing data holding1500 [ readStart="1500", readValueType="int16", writeStart="1500", writeValueType="int16", writeType="holding" ]
          Thing data holding15011 [ readStart="1501", readValueType="int16", writeStart="1501", writeValueType="int16", writeType="holding" ] 
      }
  </code></pre>
  
  <p>What am I missing to get MODBUS going in OpenHAB2. References to some tutorials or working examples will be appreciated.</p>