Single transmitter to DCS and ESD


what is the best method (wiring, devices etc) to connect one single transmitter to both DCS (for monitoring) and ESD (for 2oo3 voting with two other transmitters directly to ESD) systems, in terms of safety and reliability ?

Thank you for your comments 

7 Replies

  • Hello John,

    First of all, I would assume you have already done your risk assessment, and sharing the instrument would not impact the risk reduction you're targeting.
    The DeltaV Integrated Control and Safety System architecture allows for the transfer of a logic solver input to a DeltaV Controller over the network, which would avoid the use of splitters, hardwiring and additional I/O.
    Each SIS node has a Proxy, which is also a DeltaV Controller, if the BPCS (DCS) logic is assigned to this controller, the input transfer from the logic solver happens at 100ms rate.

  • In reply to Tadeu Batista:

    Hello Tadeu

    Thank you for your message. I am actually looking for the hardwire solution, use of signal splitter, extra cables etc ..however i am not sure of the correct and best setup in terms of safety and reliability.. any reference to typical configuration or splitter models for example.. Thank you
  • In reply to john :

    Hello John,

    If the idea is to use splitters, there are several manufacturers, Emerson does not recommend any specific one.
    Assuming you'll chose a SIL rated splitter, to correct set it up, you'll have to follow its installation manual, as well as safety manual to make sure it will fulfill the reliability spec.

  • In reply to john :

    We utilize two methods. In a number of cases, we bring the 4-20 mA directly to the Safety Logic Solver, then use an analog out from the ESD to send the signal to the DCS (through a signal isolator i.e. I/I converter). In another case we wire the ESD current input in series with the input of an I/I (there are several that are SIL rated and offer HART pass-through), and connect the output to the DCS.
  • In reply to John Rezabek:

    Hi John,
    I assume from your hardware set that you don't use the DeltaV SIS but a third party SIS PLC.
    Instead to use the expensive SIL Splitter or even the SIS AO, I would consider to connect the SIS-PLC via Modbus to the DeltaV DCS. I guess that you do not have only one signal to transmit to the DeltaV. That reduce a lot of hardware and installation cost and can save some DST-Points if you use a Modbus connection. Just a thought.
    Best Regards,
  • In reply to Michael Krispin:

    True - we only use the AO or I/I for "control" points; all the indicate-only and alarm points are Modbus.
  • As mentioned there are multi ways to accomplish this. I have found that the simplest way other than utilizing the SIS signal to the BPCS via communication is to order the transmitters with dual channel outputs and take one to each system.