title: snmp concatenation (part of an array output with oid)
body: <p>I am working on SNMP in node red.</p>
  
  <p>I want to see the callActiveCallState, so I am doing snmp table on this oid 1.3.6.1.2.1.10.21.1.3.1 to see the output of "row index".</p>
  
  <p>I am writing a function that concatenate the rowIndex from the snmp table's output with this oid 1.3.6.1.2.1.10.21.1.3.1.1.9.</p>
  
  <p>I am doing that because I need the ouput of this oid "1.3.6.1.2.1.10.21.1.3.1.1.9.row index".</p>
  
  <p>So the function that I am writing is:</p>
  
  <pre><code>msg.oid = "1.3.6.1.2.1.10.21.1.3.1.1.9";
  msg.oid += "."+ msg.payload[0]; 
  return msg;
  </code></pre>
  
  <p>but I have a problem about <code>payload[0]</code>.</p>
  
  <p>any idea? 
  Thank you in advance.</p>