Communications loops

[Indy]

We have 12 tanks each with a 7 core cable.
Core 1 live
Core 2 neutral
Core 3 comms+
core 4comms-
Cores 5 and 6 spare
Core 7 earth.

Regarding the comms we have a junction box were for tank 1 comms- is connected to comms+ of tank2 and comms- of tank2 is connected to comms+ of tank3 all the way to tank 7.

This process is repeated for tanks 8to 12

My question is:does this mean that tanks 1-7 are on one loop and 8-12 are on another loop?

Thanks

 

[MikeHalloran]

What do the comms+ and comms- wires connect to at each tank?


Mike Halloran
Pembroke Pines, FL, USA

 

[Indy]

Hi
there is a level instrument on each tank.
Thanks

 

[MikeHalloran]

There is probably a drain valve on each tank, too, but the existence of _some_ 'level instrument' per tank is equally of absolutely no use in answering your question.




Mike Halloran
Pembroke Pines, FL, USA

 

[Indy]

Hi
the 7core cable is for the level instrument and the comms for this instrument are linked in a jb. I am just curious,given the info above,are tanks 1-7 on the same loop and are 8-12 on the same loop?

thanks

 

[zappedagain]

Your description is incomplete so we can't answer your question with the info provided:

" tank 1 comms- is connected to comms+ of tank2 and comms- of tank2 is connected to comms+ of tank3 all the way to tank 7.

This process is repeated for tanks 8to 12"

So is Tank7- connected to Tank8+? If so they are on the same loop. If they aren't but Tank1+ is connected to a common point with Tank8+ then they are on the same loop, but different 'branches' of the same loop. If they are not in common then they are on different loops (unless they are tied together within equipment that you don't know about yet).

You'll need to Google the model number of your 'level instrument'. That should tell you the communication protocol that is in operation.

What is your real question? Why are you asking about the communication channels?

Z

 

[roydm]

Yes, you have two different loops, each level transmitter has an address and the control system will poll each one in sequence.
The reason you have two loops rather than one may be because they run out of Voltage or just to halve the risk of loosing all transmitters with a broken communication wire.

If we knew the full model No of the transmitter we could give you a much better explanation.

I think it's probably communicating with HART but it could be Foundation Fieldbus (usually wired in parallel) or something like Modbus.
What is the Voltage between Core 1 & Core 2? AC or DC?