Clear.Mind

Need recommendation for choosing equipment of wireless network

4 posts in this topic

Hello.I develop project and need to make stable wireless connection between 3 PLC's system. These PLCs will controll mobile crushing complex. I have added picture with simple drawing and photos. There is 3 parts on tracks. Maf and lt200 haven't any mechanical connection and can be in different distance in moving process. In stable working condition distance is about 15-20m.Lt200 and MS16 has connected between themself by two conveyors LL1,LL2. Also these conveyors can moving by wheels and changes distance. 

I have googled a lot of wireless AP, but i haven't good knowledges and expirience with indastrial wifi. Moxa equipment have too high price and i think abouto using ubiquiti AP.

What do you think about this config:

1) Central AP Ubiquiti Rocket M5 with Omni Antenna AMO-5G10 (5GHZ 10dbi).
2) Client Access Point Bullet M5 with Moxa Antenna ANT-WDB-ANF-0609 ( 2,4 ~ 2,5 GHZ  5.1 ~ 5.9 GHZ  6/9 dbi )

or better use all 3 AP Bullet M5 with more powerfull  Moxa Antenna ANT-WSB5-ANF-12    (12 dbi. 5GHZ)

Can give me advice about this config and about dbi power of antennas?Maybe give some advice with different equipment if this will not work.

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Edited by Clear.Mind

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I've never used WiFi for communication in this kind of industrial application, how critical would it be if one of the units (e.g. LT200) could not communicate with the two others (for some telegrams)?

I've always used radios in this kind of application but you say that the price tag is too high - as stated above I would say it all depends on the application and how stable it needs to be.

  • What kind of data are you exchanging?
  • How critical is it if a unit stutters, or fails to receive/send one or more telegrams? Timeouts?

In my experience WiFi is a bit less stable than radios, so it all depends on the "critical aspect" of your application. Regarding antennas, you would need to test the 100m distance, but will probably work with 2.4Ghz and Omni-Directional antennas.

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19 hours ago, kaare_t said:
  • What kind of data are you exchanging?
  • How critical is it if a unit stutters, or fails to receive/send one or more telegrams? Timeouts?

All 3 systems controls by local’s plc. Central plc place in LT200, also in this part situated operator's room  with GOT HMI. Telegrams will consist of start commands to MAF and MS16 and feedbacks signal. In case of lose communication MS16 with LT200 will activate parallel working profibus connection. For LT200 and MAF will prepared LAN cable with plug in connectors, if sh*t happened with wifi. In case if lost all communication system can works in local mode. MS16 will provide ready signal to LT200 +24V by wire, but I didn’t invent same signal from LT200 to MAF.
Old control system works via Canopen remote i/o station, lt200 with MAF via Canopen-Bluetooth convertor and works very bad, so employer want to change control's system.
I have experience with wifi connection between two parts of system via shi*y TP-LINK TL-WA7210N bridge connection (400 m)  and it works very well with 1 sec timeout via FX3U-ENET (protocol UDP, with confirmation CRC sum), but also this ap can faults sometimes. I hope Ubiquiti will work better then tp-link. 
 But I haven’t experience with omni-directional AP and don’t know how affect dbi power of antennas on quality of connection.
Why do you think 2.4 better than 5 Ghz? 5ghz have is more clear frequency domain and there are no barriers which can blocked signal or 2.4 have better omni broadcasting radius?
When did you use radio it was rs485 Modbus communication or N:N? 

What kind of raidos device did you use?

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Edited by Clear.Mind

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2 hours ago, Clear.Mind said:

Why do you think 2.4 better than 5 Ghz? 5ghz have is more clear frequency domain and there are no barriers which can blocked signal or 2.4 have better omni broadcasting radius?

Lower frequencies have a better range (and can traverse obstacles better, but you said that's not a problem for you), that's why radios are even better than WiFi (radios typically work below 900Mhz).

2 hours ago, Clear.Mind said:

When did you use radio it was rs485 Modbus communication or N:N?

I've used radios with different protocols, everything from custom made protocols to built-in Mitsubishi MC to ModbusRTU. In any way, as with wired connections, I recommend CRC and a link detection mechanism.

2 hours ago, Clear.Mind said:

What kind of raidos device did you use?

I have very good experience with Westermo/Elpro products (but the price tag will be quite different than the ones you are looking at with Ubique):
http://www.westermo.co.uk/web/web_en_idc_uk.nsf/AllDocuments/EA2D04A31E9C89D0C1257A7D002F8B59
http://www.westermo.com/web/web_en_idc_com.nsf/AllDocuments/9DC2AE62E055E36DC125788E00498DB9

 

All in all it depends on the critical aspect of your application. I'm not saying that WiFi won't work for you, I'm just saying that radios are a more reliable choice. I would also consider the temperature rugged equipment requirements before purchasing any equipment (doesn't matter if you go with WiFi or radios - make sure you get the industrial spec you need).

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