I was thinking today about cats. Now, let it be known to all
here and beyond, that I really dislike cats. I think they are arrogant, selfish
and egotistical. If you’ve ever talked to one, you know that to be true.
But even though I dislike them, today I was thinking about
cats and why they have nine lives. Of course, I consulted Mr. Google and found
this rather interesting explanation:
One day, a very hungry cat entered
a house and found a plate of nine fish that were going to be eaten for dinner by
the nine starving children who lived there. The cat was feeling a little
selfish that day and ate up all of the fish in nine quick bites. With no food
on the table, the nine starving children died of hunger the very next day,
along with the cat who died from eating WAY too much. When the cat went up to
heaven and spoke with God, God was so angry with the cat that he threw him out
of heaven and made him fall for nine days all the way back to earth. To this
day, the cat still holds the nine lives of the starving children in his belly,
which is why he must die nine different times before he will stay dead.
Thinking of what else lives long lives made me think of “Grandpa
Modbus”. I call it Grandpa Modbus because it’s been around this industry since
before I ever walked on a plant floor and that goes back a ways now. In fact,
the project to develop Modbus began way back at Schneider Electric in the
middle 70s. That was the decade of Watergate, it’s when the Beatles broke up
and when Elvis died. And it’s when I was wearing an orange leisure suit (don’t
ask – the pic is gone forever).
In the midst of all that tragedy, especially the leisure
suit, Modbus was birthed. And it lives a long, long life with no signs of Alzheimer’s
or losing any steps. People are still using it today as much as ever but, I’ll
concede, some of that growth is from its preppy grandson Modbus TCP. By the way
if you’d like to learn about Modbus you can view the award winning Modbus video.
Or you can read about serial
Modbus RTU or Ethernet Modbus TCP.
So what keeps this grandpa young and spry? Here’s what I
1. Easily understood data organization. Modbus data
is flat. Just a bunch of registers and coils. Non-programmers can easily
2. A few simple commands. Modbus is simply command
response. A master sends this function code and the slave responds like this.
Almost anybody can understand it.
3. Very straightforward encoding. The way that the
commands and data are put on the wire is concise and uncomplicated.
And there’s more.
But what I’m really talking about here is simplicity. Like
everything else, simple always wins. Life is too complicated. Everything is too
complicated now days. From the cell phone to showers [I have a customer that is
adding web controlled Lights, Music, Vibrations and Temperature adjustments to
their offering.] All that is too much for me.
And because of it’s simplicity Modbus will always be out
there. That old man is going to live forever. And if you have Modbus in your
facility, here’s some products that will help you move it to your other
– this product makes a ControlLogix PLC look like a Modbus Slave to your Modbus
– this product connects to a bunch of Modbus RTU Slave devices as a Master and
moves data from those devices into a ControlLogix PLC
460PSMM – this product does the same thing for a Profinet IO
network. Data from one or more Modbus slaves can be moved into a Profinet IO
That’s just a sample. There’s more if you look at our full line of Industrial