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Multiple U12 connections


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2 replies to this topic

#1 Akilan

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Posted 28 May 2013 - 06:09 PM

Hi, wanted to control about 800-1000 relays 24VDC using U12, in that case total no of U12 will be around 40-50 Nos. whether its possible to connect via USb HUB, whether the USB will be able to transfer all the digital output (1000) at a single go or the outputs has to be sent sequentially for one DAQ at a time, Kindly suggest on this. I will be using Labview for my application development. Regards Akilan

#2 LabJack Support

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Posted 29 May 2013 - 03:32 PM

USB is specified for 127 devices per host, so using 50 U12s is possible. The most we have tested with on a single host is about a dozen, and we had no problems. USB is a serial bus, so you would talk to them sequentially. Also consider the U3 rather than the U12. Another possibility is using a smaller number of LabJacks to control a bunch of I/O expander chips such as the MCP23S17. What type of relays are they? 5V control and 24V output? Solid-state or mechanical?

#3 Akilan

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Posted 30 May 2013 - 12:22 AM

USB is specified for 127 devices per host, so using 50 U12s is possible. The most we have tested with on a single host is about a dozen, and we had no problems. USB is a serial bus, so you would talk to them sequentially.

Also consider the U3 rather than the U12.

Another possibility is using a smaller number of LabJacks to control a bunch of I/O expander chips such as the MCP23S17.

What type of relays are they? 5V control and 24V output? Solid-state or mechanical?


Realys are mechanical having a coil excitation of 24V Dc. I choose U12 since the digital output high level is 5V, since i will be using
an opto isolator which works on 5V and switches the 24VD.C to the relay.


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