RoadTest: IMO iSmart
Author: danielw
Creation date:
Evaluation Type: Independent Products
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: Our own MCU controller.
What were the biggest problems encountered?: Serial cable not present, and its a serial cable!
Detailed Review:
I've been trying out the IMO iSmart SMT-CD-R20 for the last few weeks and have been trying it in several applications where I already have something in place to compare it to.
First impressions are that it looks neat, well made, There are different voltage versions 12, 24, and 110 / 240V AC. Relay, and transistor output options, modules, PWM, in fact there is a good choice of modules that will get a lot of projects running.
However I'm really disappointed by the serial connection. I don't want to be carrying around another cable that will at some point break or get cut when a door is closed on it. Also on site I use a laptop that doesn't have serial ports, so now I have to carry around a USB - serial dongle as well. I have seen that an iSmart with USB will be available but really it should have been there from the outset.
As it is, I couldn't wait for a cable and after about an hour messing around with the scope, I figured out what was going on and made a cable using a USB to TTL serial converter and a few bits of wire.
It also gave me an excuse to open the unit up!
To Be Continued...
So, some while after the initial play with the IMO smart I've had chance to give it a more through test. My application was a rather simple test rig, but helped identify some of the strengths and actually made me appreciate the IMO smart much more than I thought I would.
I generally come at a project with the idea I can use one of my previous designs with a few mods or hack a prototype board together. The financial team also like this as I generally have the bits in my back room and so there isn't much of an financial outlay.
This time however I did things differently. I started out trialling the IMO using Functional block diagram mode (FBD), Ladder logic being something I've never used nor intended to use as it seemed so different to what I was used to. FBD however seemed to fit my electronic background so I dived in.
Quite quickly I had a system that could repeatedly test the extension and retraction of one of our recoiling products. Basically operate the motor until a limit is reached, reverse the motor until the first limit is reached and increment a counter. Repeat this until a stop situation is encountered, either the stop button or a loss of continuity.
Given that my traditional way of doing somethinng like this I would have taken a processor, some bread board, relays, software e.t.c. I was up and running with a basic test kit within a couple of hours.
Since then I've had a few goes at ladder logic, and had the opportunity to do a more complex machine control that had to expand on the existing ladder logic program. It took me a couple of hours to get the ladder logic basics. Understand timing issues relating to when inputs are being read and how the logic elements are processed. Over the next few weeks the code was extended to incorporate more features, and while different to what I'm used to, once I understood the concepts, I actually found the ladder logic quite easy to use and quite quickly got a useable system. I've had a few issues with reacting to very quick inputs and then doing something with that input. Something I could have done easily using a processor and interrupts if necessary. However after a bit of thought I managed to work around this.
So in conclusion, most of the test applications I currently use processor for would run perfectly well on the IMO Smart. And given the shorter development time to modifying an existing design it would actually save money. I will definately be using a smart relay again for future control applications and will be using ladder logic so I can develop my use of the language. I've not made much use of the display, but have used it for basic information. I want to expand on this for the next piece of test hardware I develop.
I think the availability of a development kit and training would be advantageous for a first timer. I used some switches, and led's to try out the basic concepts. I also used the software simulator to great effect.
Finally. Thank you to Element 14 for allowing me to trial the hardware. I started out rather blinkered against PLC's but ended up gaining a lot of respect for what is a usefull piece of hardware. (Still should have had a USB port for programming though!)
Dan.
Dan.
