Answer / nileshkumar jambukiya

1)IOP means input open, when process velue (PV) is out of
renge (20 ma) then IOP alrm comes,

2)when PV is small then minimum range (LRV) less then 4ma
then IOP- alrms come,

3)when cable short or open from loop then same alarm come
iop-,

Answer / osagie

IOP Faults are very common in any Yokogawa Fieldbus setup.

As rightly stated in Ans 1, it means Input Open. The idea here is that there is an open circuit somewhere. The circuit here may be the physical circuit or the logical circuit. By logical circuit, I mean the control drawings.

Now lets look are typical scenarios and solutions:

1. Transmitter input over ranged: For a transmitter that is supposed to transmit up to 100%, if its getting a 110% input, it goes on IOP (+) but you will not see the + most times. Under ranged transmitter would give IOP-.
Solution: Get the transmitter input back to the normal range.

2. Consider a control loop with a transmitter input to a controller. whenever the transmitter fails, the controller will give an IOP fault i.e reporting that its input is open - in this case, check the transmitter and possibly change it if bad.

3. Sometime control valves give IOP when they are faulty.

4. Loop component failures can also cause IOP. Check components like the Mega blocks, connectors etc

In general, initial troubleshooting will be re-downloading the control drawing. You can also perform reconfiguration of the Fieldbus devive.

Hope this clarifies.

Osagie.

Answer / jigaranadkat

1) Infield bus system, IOP detection is different from HART system.
2) IOP will occur only for input e.g. transmitters.
3) One probability is there (which is most common) that your transmitter is under-ranged or PV value fluctuates highly (on wither ends). Being s digital system you will not receive IOP(-) in FF system.
4) Check for alarms and run integrity test (via PRM) and check if any of the internal blocks like AI or Transducer block or Resource Block is going to OOS (Out of service or Manual Mode).
5) Additional Check :

Check if you are receiving CNF error. If it comes then you may reset the transmitter by removing the power or isolating it from Loop.
This shall resolve the error. If not then you need to replace the transmitter.

Hope this helps.

Answer / abdulcader

FF device signal is a communication signal.If any noise or jetter valve are high.it will affect the total segment and time to time particular segment's all devices will go iop.

We can diagnosis the problem by using FFADM[FFadvanced diagnosis module] or fieldbus monitoring device FBT6.

Mostly diagnosis noise valve high in barrier.If you replace the barrier 90% problem will solve.  

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