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Click PLCs / Mango
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Has anyone used AutomationDirect's Click PLCs with Mango?
If so, any suggestions / comments / issues?
I hope on using the Modbus TCP protocol -- anyone have any idea what the max polling speed on something like that is?
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Hi rshah,
I personally do not have experience with the poll timing question specific to that PLC, but...
I would expect it to be something you could poll very quickly. Mango doesn't offer sub-millisecond options and we don't encourage people to use 1ms (unless you want to see what happens, then go for it!). You should have your edge device timestamping if you seek that precision. Mango records time for data in their milliseconds. You could expect a minimum poll time 10-250ms depending on what you've setup (if they're in relatively close network proximity, how much data in how many requests (data source settings)). You may wish to change your NoSQL settings to have a larger small batch insert size, and a larger small batch insert delay, if you poll very quickly.
Modbus can only request from one register range in a single request and ranges are requested sequentially, so if you're really looking to go fast you may want to mirror coils in the holding registers, for instance, to read everything in one request.
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@phildunlap said in Click PLCs / Mango:
Modbus can only request from one register range in a single request and ranges are requested sequentially, so if you're really looking to go fast you may want to mirror coils in the holding registers, for instance, to read everything in one request.
You are the best, Phil. Thank you!
We will post an update when we try the Click and let everyone know how it works!
We're hoping to measure incoming line voltage in our building to monitor for intermittent fluctuations so the faster the poll time the better, I think.
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@phildunlap said in Click PLCs / Mango:
I personally do not have experience with the poll timing question specific to that PLC, but...
Out of curiosity, is there a PLC that you guys recommend, or have worked with and like? Preferably one that supports BacNet?
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Hi rshah,
Just to chime in on your question - what are you using to measure the incoming line voltage? If it's an actual metering device or transducer, then the response time of that will probably be the bottleneck when it comes to the frequency at which you can get new, meaningful voltage values from it.
I don't know what the Click PLC might add on top of that, but I imagine Modbus TCP is going to be your best bet for quick polling (network traffic notwithstanding) versus the added overhead of BACnet/IP. All said, you're probably going to be looking at something around 100ms being your maximum reasonable polling rate. To get anything more granular than that, you'd probably need to consider a power quality meter specifically made to detect and log voltage events down at the cycle/sub-cycle level and those usually start at a couple thousand dollars, if memory serves.
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I've been using Accuenergy Acuvim IIR power meters. They support Modbus RTU by default, but you can plug an inexpensive Accuenergy module to the back of the Acuvim that supports multiple Ethernet protocols. They even report harmonics, if that's what you need. Some models are headless; some have LCD front panels; some have built-in data logging. I bought direct from Accuenergy, but you can also find them on Amazon for $500 ~ $600.
I've also been considering using CLICK PLCs, but be warned that you will have to set up registers for every function, whereas a power meter will have hundreds of power-specific registers. If you need the PLC just for remote I/O rather than for local control, it may make more sense to add one or two I/O modules to the back of an Acuvim meter instead. If I need local control that will still work if the connection to Mango is lost, then I would use a PLC.
I look forward to hearing your experience with CLICK PLCs, as I've been considering using Ethernet CLICK PLCs in a couple of locations.
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We just installed a ClickPLC and are using Modbus TCP.
This connection is going through a single hop through a Cisco switch.
Right now I've only configured 1 point as a test.
For our 1 point, I just checked with a 25 ms update period, and it's been stable for the past 10 minutes, as I haven't seen any errors on Mango's side.
I'm sure how the polling is affected with more points. I plan on polling at 250 ms, as that is more than adequate for our needs.
