Host Engineering Forum

General Category => DirectSOFT => Topic started by: Harvey on March 16, 2010, 09:23:33 AM

Title: thermopcouple f4-08-thm-n
Post by: Harvey on March 16, 2010, 09:23:33 AM

New to direct soft.  I need to drive the input high if there a thermocouple is disconnected or shorted. any ideas

Title: Re: thermopcouple f4-08-thm-n
Post by: Gene Bond on March 16, 2010, 08:30:19 PM

Forgive me, but I've not used this card, but couldn't you do do a couple of compares that are out of your normal range for alarms? Seemsif the T/C is shorted, the register would read very low, surely lower than normal for the process, and if it's open, it should read very high...

Again, maybe not applicable, but it may help.

Title: Re: thermopcouple f4-08-thm-n
Post by: b_carlton on March 16, 2010, 10:10:31 PM

The manual defines that there are "Broken Transmitter Bits".

As far as 'shorted', Gene's suggestion to test against any possible normal measurement is a good one. Be aware though that a shorted thermocouple - the two leads shorted together at some place other than the normal measuring end - will measure the ambient temperature at the shorted point.

Title: Re: thermopcouple f4-08-thm-n
Post by: Harvey on March 17, 2010, 07:56:35 AM

Open it is reading low, if I unwire the t/c it will read 92 deg what I would like this be a read high so the heater does not keep trying to heat.  Other plc cards I have used have a way to configure this; I have not worked much with direct soft.

Title: Re: thermopcouple f4-08-thm-n
Post by: b_carlton on March 17, 2010, 08:49:37 AM

I repeat:

Quote

The manual defines that there are "Broken Transmitter Bits".

It's not a function of Directsoft. It's a function of the thermocouple card. Read the instructions carefuilly.

Title: Re: thermopcouple f4-08-thm-n
Post by: Harvey on July 31, 2010, 01:43:57 PM

 yes it is "Broken Transmitter Bits"in on the f4-08thm not the -n. On the f4-08thm-j card it is to go high same as burned out thermocouple this is staying at 95 deg when the termocouple is unplugged. 

Title: Re: thermopcouple f4-08-thm-n
Post by: Controls Guy on July 31, 2010, 01:53:05 PM

There is no F4-08THM-N listed as a part number on the website.

Title: Re: thermopcouple f4-08-thm-n
Post by: b_carlton on July 31, 2010, 02:37:16 PM

The 'F4-08THM-N' is a shorthand for either of the older cards F4-08THM-J or F4-08THM-K which were single single type thermocouple specific. The (I believe) newer F4-08THM accepts a variety of thermocouples.

Title: Re: thermopcouple f4-08-thm-n
Post by: Controls Guy on July 31, 2010, 04:11:24 PM

Oh, sorry, I assumed it was a module specific to Type N thermocouples analogous to the J and K-type cards.

Title: Re: thermopcouple f4-08-thm-n
Post by: Harvey on August 02, 2010, 09:22:36 AM

My understanding is with the F4-08THM card you can set up each channel for a different type of thermocouple with a jumper, thank you for all the help and input.   :D