• Not Answered

edc and DC blocks issue

Hella all,

We got a message from Emerson with the following issue:

DC/EDC block outputs get written on a “one shot” basis on a change of state when those outputs are configured internally to the block and all outputs have good status. If an output has bad status, it’s possible for a change of state to not occur, preventing new output values from being re-written. This may also prevent the operator from manually changing the state of the function block, requiring manual operator intervention at the physical device.

The following conditions must all be true to be susceptible to this issue:
• Configurations utilizing DC or EDC blocks with outputs tied directly to I/O channels. (Wired outputs to Discrete Output function Blocks are not susceptible.)
• More than one output is configured and assigned directly within the DC/EDC block.

Using CHARM I/O
• The status of an associated Discrete Output CHARM goes bad for any reason as reported by DeltaV.
Using Conventional I/O
• DC/EDC Block Outputs are tied to the same Conventional DO Card and one of the channels has a field wiring fault where LINE_FAULT_DETECTION is enabled for the affected and associated channel.
OR
• DC/EDC Block Outputs are tied to Conventional DO channels spanning multiple cards with one of the cards having a bad status affecting the channels as reported by DeltaV.

However, we don't know if it is relevant for us. 

I don't understand the statement:

Configurations utilizing DC or EDC blocks with outputs tied directly to I/O channels. 

In our software we are using classes, which contains DC functional blocks in which the IOs are defined (see picture).When we are configuring our DC modules as shown below, do we need to modify our modules?

Hopefully somebody can reply on this.

Thank you in advance.

Best regards,

Elwin

1 Reply

  • IO_IN_4/IO_OUT_1/IO_OUT_2 are directly tied to DC Block, you should use Discrete Output function Block to ty them.