A friend of mine asked me to take a look at these little industrial wireless access points and give him my honest thoughts/opinions on them and their practical uses. So, I brought them home and fired them up on the workbench to see what they were all about.
The WAGO 758-919 is a small, dual band 802.11 wireless access point that is also Bluetooth capable. It can function as a standard wireless access point/gateway, or as a wireless bridge and has an internal omni-directional antenna. It comes in a small form factor that is designed to be mounted on/through the side of a cabinet.
The two power options for these little guys are 19 to 36 VDC or standard Power over Ethernet (802.3af) from a switch or PoE injector. This makes these pretty versatile for multiple kinds of deployments.
The design of these small radios lets you install them on any surface of the box you are placing them in. Top, side, front or bottom of a panel box are all viable locations for mounting. However, you need to be aware of the limitations. Let’s take a look at the antenna radiation patterns in both 2.4 & 5GHz.
On the left is the radiation view as if you were looking down upon the top of the access point. This shows you the signal coverage in a horizontal plane view. The blue line represents 2.4GHz and the orange represents 5GHz. From this perspective, 2.4GHz is broadcast in a solid 360-degree pattern all around the access point. 5Ghz on the other hand, not so much. It is really acting more like a semi-directional at approximately 190 degrees or so as opposed to an omni at a full 360 degrees.
On the right is the vertical radiation view, as if you were looking at the side of the access point. From this perspective, neither 2.4GHz or 5GHz are broadcasting in omni-directional fashion. 2.4GHz looks to have an approximate 120 to 130 degree beamwidth, while 5GHz is at about 90 to 100 degrees.
So, what does this mean? It means that to get the best overall coverage performance out of a WAGO 758-919, it should be mounted to the top of what ever box it is being installed on. This isn’t an absolute though, as different factors can influence installation choice. For example, if all that is needed is a small area of coverage for technicians to connect to the cabinet wirelessly with a tablet or other client device, the top mount would be optimal. However, if a direct line-of-sight point-to-point connection is desired between two panel boxes, then a side mount could be in order.
The point is that being familiar with a radios antenna radiation patterns increase the likelihood of a successful deployment.
The WAGO 758-919 is capable of both 2.4GHz and 5GHz, but not simultaneously. So, while it is in dual band in spirit, in actuality it can only broadcast in one single band at any given time.
It has two wireless operational standards:
- 802.11 for standard WiFi access and wireless bridging
- 802.15.4 Bluetooth and Bluetooth Low Energy (BLE)
In WLAN mode (802.11) this device can be used as a standard access point for local wireless access, complete with a configurable DHCP server should you need it. In general though, I recommend against running DHCP on OT networks. This mode can be run in 2.4GHz or 5GHz, your choice. Additionally, it can be set into bridge mode for point-to-point connections. This is great for connecting different systems that are relatively close together without having the expense of running copper cabling.
So how much bandwidth can be pushed across these devices? That’s a great question. I stood a pair of these radios up in my lab on my development network to test this very thing.
These tests were performed in my lab which is a controlled setting with low wireless contention and virtually no non-WiFi based interference. Your experiences will vary depending on the environment you install them in.
My bandwidth testing software of choice is jperf. It is essentially the same iperf we all know and love but wrapped in a nice little GUI for ease of use on Microsoft Windows computers.
Before I get into the testing I should probably let you know what the WAGO paperwork claims about throughput and performance. These are 802.11n radios and in Access Point and Bridge modes the manual claims a MAX Link speed of 65 Mbps with a net data throughput of 20 Mbps.
The tests I performed were:
- Access point mode (802.11n, SISO, Max EIRP of 15 dBm)
- 2.4 GHz wireless client to workstation on the development LAN
- 5 GHz wireless client to workstation on the development LAN
- Bridge mode (802.11n SISO, Max EIRP of 15 dBm)
- 2.4 GHz wireless bridge connecting hard lined clients on either end
- 5 GHz wireless bridge connecting hard lined clients on either end
In Access Point mode on 2.4GHz the average throughput rate was 14.07 Mbps while 5GHz was 26.21 Mbps. Attached here are the full jperf test results:
It’s interesting that the net throughput is listed as 20Mbps considering the differences of the values between the two frequencies that I recorded here in the lab. If I average the averages (is that even a thing?) of 2.4GHz and 5GHz it comes out to 20.14Mbps. So, it would seem that the documentation is right on point from that perspective.
In Bridge mode on 2.4GHz the average throughput rate was 10.22 Mbps and 5GHz was 15.86 Mbps. Attached here are the full jperf test results:
Obviously, in Bridge mode there seems to be a significant decrease in overall throughput in both spectrums. I can only guess that it may be due to the extra overhead required to maintain a bridge link across two of these radios that have very limited hardware resources available to them.
In Bluetooth and Bluetooth LE (BLE) states the only operational mode allowed is essentially bridging in where the radio can be either a Bluetooth Client or a Bluetooth Access Point. In AP mode it is capable of handling up to seven Bluetooth clients in a star type topology. The “gotcha” on this is that they can only connect to other WAGO 758-919 devices due to how they handle the protocol internally.
The benefit to using Bluetooth is increased range and frequency hopping for reliability. The downside is that net throughput is very limited. In fact, the documentation states that throughput for Bluetooth Classic is 1Mbps while BLE mode is 200kbps.
For testing purposes, refer to the bridging topology pictured above with the understanding that one WAGO device was in Bluetooth Access Point mode and the other was in Bluetooth Client mode. Additionally, the disclaimer previously stated holds true for this testing as well.
In Bluetooth Classic mode, average throughput was .95Mbps, which is on par for what the documentation states. With BLE testing, I could not seem to get the configuration correct as after multiple tests I was getting similar results as compared to classic mode, which is much higher than the aforementioned 200kbps limitation of BLE. That being said, I did not include its testing. Attached here are the full jperf test results for Bluetooth Classic:
The web interface of the WAGO 758-919 series is straightforward and intuitive. WAGO did a good job of keeping it clean and simple to navigate and use. Having never seen or handled one of these specific devices before, I had the first access point up and running on my development network in about ten minutes. Click the links below to view some screen grabs of the user interface.
Personally, I see these as “no frills” radio devices. They are not built for high throughput, but for basic connectivity. Granted, most of the applications a radio like this would be used for would have low data rate requirements anyway. I do like the small form factor and the different power options which adds to its versatility.
If you are looking for a lower cost (average retail price online is approximately $525) option for either basic wireless connectivity to a cabinet or wanting to save some money versus having copper run between two or three cabinets for low bandwidth communications, then these are a solid choice. Especially since their antenna is internal and the device, once mounted properly, is IP66 rated.
If you need something with high throughput values, long distance connections or larger IIoT style deployments, then these are not ideal.
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