Product Review: Siemens Logo! 8

Logo Smart RelayTo those who have read my previous posts you know that I really like smart relays. The simplicity, ease of troubleshooting, and flexibility make them a winning solution. I recently had a chance to test drive the Siemens LOGO! 8  smart relay

To start, download the free SoftComfort demo software, it is  a complete package, lacking only the ability to write a program to a controller. With the demo you can play around and test out all the functionality, and there is a lot of it to try. 

In the relay itself is as well built as its cousins. The screen is bright and changes colour to notify the operator of the device status quickly. I personally wouldn't want to program a complex program directly using the screen on the relay but it is suitable for making small logic changes.

Altering parameters such as the duration of timers or analog set points is easy and appears in a self contained menu making changes intuitive. Taking the time to name the blocks correctly when setting up a program makes field changes to values intuitive especially if multiple timers or setpoints are used. 

When using the new LOGO 8 take advantage of the android app. It allows full control of an ethernet connected smart relay from a remote device. A great example of applications for this can be found here. 

At the end of the day, a relay is a relay and it all comes down to the software suite to differentiate. The LOGO! SoftComfort software doesn't disappoint. It is modern looking, gone are tiny text boxes and courier font infographics often seen in . Built-in it includes dozens of pre-built function blocks making it simple to develop logic quickly, the drag and drop interface is  convenient.

Using a network cable to program the unit takes a bit of tinkering, setting up the IP addresses correctly in the unit and software is critical to getting the system to talk. The defaults are fine if the the computer you are using has only one network connection, if your PC is connected to the internet and a smart relay at the same time you may need to hit up IPCONFIG in a command line to get the IP address and Subnet Mask in use and make the necessary changes within the Network Menu of the LOGO. 

Available for download are numerous application examples which provide a great introduction to function block program design. The SoftComfort software will convert ladder logic to function blocks which is great for trial and error learning. 

To sum it up, this is a great device. It allows an entire control panel of timers, relays, and dedicated controllers to be replaced with one small (71.5 x 90 x 60 mm) package. 


James Jenkinson, 


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