Temperature loops shows IOP (input open) in the YOKOGAWA DCS even though the physical connection from the sensor to the system are all OK.

I'd like to know what are the possible reason.

 

1) loops = plural
sensor = singular

Is this problem occurring on more than one point?

2) A sensor is usually connected to a field (loop powered) transmitter. The loop powered transmitter needs a power supply.

Or is this setup thermocouple or RTD direct to an analog input?

Which type sensor?

How do you know the transmitter is properly configured?

3) How do you know the loop is wired properly?

Do other points using the same power supply work?

4) How did you prove "sensor to system OK" when you can't 'see' the point? What method? What was the result?

5) How do you know the DCS point is mapped to the analog input/slot/rack you think it's wired to?

 

Ooops.

I entirely missed "Foundation Fieldbus" stated in the header on the forum. FF didn't show up in the message.

I'm clueless on FF issues.

 

>1) loops = plural
> sensor = singular

>Is this problem occurring on more than one point?

*Yes, so many temperature loops have this kind of problem.

>2) A sensor is usually connected to a field (loop powered) transmitter. The loop powered transmitter needs a power supply.

>Or is this setup thermocouple or RTD direct to an analog input?

*It has transmitter, RTD is connected to transmitter.

>Which type sensor?

*RTD

>How do you know the transmitter is properly configured?

*It is properly configured, loop test has been done by simulating signal on the transmitter. Since the simulated signal is read on the DCS, thus there is no problem with the configuration.

>3) How do you know the loop is wired properly?

*Yes it is wired properly, otherwise we can't read the simulated PV on the DCS.

>Do other points using the same power supply work?

*Yes it is.

>4) How did you prove "sensor to system OK" when you can't 'see' the point? What method? What was the result?

*Loop test has been done by simulating signal on the transmitter (without element). After that, construction team install the TE and connect the wire to the transmitter. Tell me, physical connection from the sensor to system is not complete yet?

>5) How do you know the DCS point is mapped to the analog input/slot/rack you think it's wired to?

*No problem with the mapping/configuration, otherwise we can't see the value of the simulated signal from the transmitter.

 

Hi there,

I think there might be something you can look at based on your feedback below.

"*Loop test has been done by simulating signal on the transmitter (without element). After that, construction team install the TE and connect the wire to the transmitter. Tell me, physical connection from the sensor to system is not complete yet?"

For information, it is possible, depending on the method used, to simulate a signal and see it in the CCR but when the TT is connected it will not work.

You are not really give much detail on how this simulated signal was done, HART, mA source or decade box but no matter, it still seems like a DCS configuration problem to me.

If the input setting on the DCS is set to "source" and the transmitter is "sinking" it will not work and visa versa. If it is a common problem on all the TT's, go and have a look how the other working loop powered PT's or FT's systems have been configured in the DCS (sink/source) and make sure the TT's are setup the same.

 

Check out these discussions on the Fieldbus forum

http://forums.fieldbus.org/showthread.php?t=895&highlight=iop

http://forums.fieldbus.org/showthread.php?t=2656&highlight=iop

 

@ first place look if resource block is in o/s mode. (this can be done from fieldbus builder or 375 terminal or from PRM station if u have one. If this is ok, then look for o/s in ai block. Give a control draw download if required. this should solve 99% of problems.

Worst case, remove the instrument from builder and configure it again

 

Put the resource block in Manual and then back to Auto. This will solve u r problem. The resource block might have gone in manual.