title: rrdtool help for simple step graph
body: <p>I'm trying to trace the status of a line, I have two values, the signal strength 0-5 and the connection status (connected = 3, disconnected = 1), the values are read every minute and I want to keep track of a year.</p>
  
  <p>Currently when there is a change in one of the two values the change in the graph is not clear, I see that a half step is almost always added, instead I would like the graph to exactly reflect the state of the values, if the power goes from 4 to 5 I would like to see it in the graph with a vertical step, without added half steps.</p>
  
  <p>I did several tests following the documentation and tutorials but obviously I am missing something.</p>
  
  <p>Database creation</p>
  
  <pre><code>rrdtool create db.rrd \
  --step 60 \
  DS:rssi:GAUGE:120:0:5 \
  DS:wan_state:GAUGE:120:0:10 \
  RRA:MIN:0.5:1:525960
  </code></pre>
  
  <p>Update</p>
  
  <pre><code># $TS is the timestamp, 4 the signal power, 3 the wan connected
  rrdtool update db.rrd -t rssi:wan_state $TS:4:3
  </code></pre>
  
  <p>Graphs</p>
  
  <pre><code>rrdtool_graph() {
      secs=$1
      span=$2
      rrdtool graph graph-${span}.png \
              --start=now-${secs}s --end=now \
              "DEF:rssi=db.rrd:rssi:AVERAGE" \
              "DEF:wan_state=db.rrd:wan_state:AVERAGE" \
              "AREA:wan_state#0000FF:Internet" \
              "LINE1:rssi#00FF00:Signal" \
              &gt;/dev/null
  }
  
  rrdtool_graph 3600 hour
  rrdtool_graph 86400 day
  rrdtool_graph 604800 week
  rrdtool_graph 2629800 month
  rrdtool_graph 31557600 year
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/fGKvu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fGKvu.png" alt="enter image description here"></a></p>