How to connect economical 30 sensors to s7-1200?

How  to connect  economical 30 sensors to s7-1200? With RS-485 or 4-20mA? (Which is required in the case of RS-485?)

Thanks

Hello,

what are that sensors? What communication protocol can work? With RS-485 medium they have each own communication box or they are connected with some numbers to each communication box? What refresh time you can imagine to be enough? In my opinion on analog side it must be also pay attention to 2 or 4 wire wiring, simply in case of 4 wire - more resources to cards so also this is important. Your question isn't so simple as it looks like.

Bill1777

1) sensor has both built-in output RS-485 and 4-20mA (2wire)

2) refresh time - 3 min

3) communication protocol don't know yet

  

 Sounds like half of the people in my office, especially the 3 minute update time.

Hello,

ok, that RS-485 is very general, it can be anything with that protocol - Modbus RTU, Profibus, other... Try give that protocol info, due this is needed also select communication card.

Update: Jeff, democracy is wide area, maybe fun? Same situations happened to me, maybe someone from your office-friends?

sry offtopic Jeff HAHAHAHAHA good answer my friend.

Ok, back to problem, good that 2 wire connection, it can solve more problems with resources in case of select analog. In my opinion I'll be pick that comm solution, but I'm curious about that protocol and length of complete bus of course. Also hope some Experts can give you another solution.