Actions
Forum Thread Details
  • Replies 42 replies
  • Subscribers 392 subscribers
  • Views 3385 views
  • Users 0 members are here
Related

Circuit Review

s1buell

  I`m currently making some proto circuits and I would love some feed back/Ideas etc.

 

All these circuits will connect to Arduino or Arduino compatible devices.

 

Anyone have time to help out with some reviews?

 

First circuit is a 4-20ma board

Parents

  • Ok, I`m going to rework the 4-20 area utilizing the LM358. I`ll post the idea later. If you have time can you review this Rs485 circuit? Its intended to connect ModBus type devices.

     

    I added high speed optical separation from the pic to Rs485 chip. I as going to add complete power separation on the RS485 in side but I stopped due to this being a test unit.

     

                                        image

Reply

  • Ok, I`m going to rework the 4-20 area utilizing the LM358. I`ll post the idea later. If you have time can you review this Rs485 circuit? Its intended to connect ModBus type devices.

     

    I added high speed optical separation from the pic to Rs485 chip. I as going to add complete power separation on the RS485 in side but I stopped due to this being a test unit.

     

                                        image

Children
  • in reply to s1buell

    Tom,

     

    I am not sure that the isolation that you have designed will do anything.  The 485 transceiver will take the hit if anything happens on the bus.  It is extremely unlikely that anything is going to get past the transceiver.  The only way that the opto-isolators would be helpful is if the transceiver was also isolated on a separate power supply (along with the transceiver side of the optos).

     

    What I would do, is attempt to protect the transceiver with a transzorb(s).  One bidirectional transzorb between the A/B pins of the transceiver, along with optional transzorbs from the A/B pins to the power rails.  Also, I would land a resistor pad(s) across the A/B pins with a jumper, to allow the module to be a terminated if it is the end module on the bus (I like this better than placing the terminator at the connector).

     

    Gene