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INTERNAL TEMPERATURE SENSOR


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Hi..

Has anyone else experience problems with the Vision internal Temp Sensor reading about 20 degrees C high. I have V570 s reading over 20 degrees high compared to ambient. I have the same program in other PLCs reading correctly. (SI and SB 14)

Where is the sensor physically and can it be affected by the snapon used etc?

jh

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  • MVP 2014

Hi John,

The V570 develops more heat than some of the older models like the V290. If it is locked in a box the internal temp may get noticeably higher than ambient, particularly if the box is sitting face-up rather than vertical.

Does this tally with what you are seeing?

Simon

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Hi John,

The V570 develops more heat than some of the older models like the V290. If it is locked in a box the internal temp may get noticeably higher than ambient, particularly if the box is sitting face-up rather than vertical.

Does this tally with what you are seeing?

Simon

Simon...

We have circulating fans in the cabinets , same for all PLCsbth with correct display and without. PLC is Vertical

I even let one run with the cabinet open all day, it is ina computer room running the environment controller so the temp inside is a stable 22 but it still reads 42.

I have added a corrrection subtract to the program but still an inconistent result between identical PLC's of same config and model in same application. Just delivered 6 months apart.

John

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OK, so sounds like something is not right.

Do you have any V570 units that record the correct temperature (or close to it)?

Are you saying that you have two V570 plcs that are showing temperatures that are both way off, and they are also quite different from each other?

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The real question is "where in the V570 is the internal sensor located and what is it's purpose?" If it's near or on a power device, then a 20 C rise is not unusual, but may indicate an early warning. I don't think this value was ever intended to be an ambient temperature indicator.

This is one for the Creators. Stein? Emil?

Joe T.

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Thanks Everyone.

I have 13 570's running the same application. They are being used as Environment Controllers in Telecoms Eqpt Rooms and Remote Telecoms Cabinets primarily supervvising the Aircons. The internal sensor was a good simple way to monitor local temp and to track it and raise a gross overtemp alarm.

I have applied the correction patch to all of the PLC's and in identical environments over 10 remote cabinets it ranges from 7 degrees over to 20 degrees over ambient. All cabinets are running a stable 30 degrees internally, (external ambient can go to 50 so the internal is deliberately higher).

There are also an additional 3 controllers looking after Equipment rooms. One 570 was delivered in Late 2009 and the balance were delivered mid 2010.

Of all of the controllers the one delivered in 2009 is within 2 degrees which is totally within expectation considering it was not realy meant to measure external temperatures.

This is not a big problem however I thought it was worth bringing to the forum

John

post-2415-028898600 1304730110_thumb.jpg

post-2415-038530700 1304730137_thumb.jpg

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Hi,

The cold junction is for when using a snap-in with a thermocouple input. It is located on the connector and measures its temprature.

post-130-064494300%201304856154_thumb.jpg

When using a thermocouple, the temperature of the connector needs to be reduced from the temperatue input value in order to get the actual wanted temperature.

post-130-064494300 1304856154_thumb.jpg

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Hello Stein

Although I didn't ask the original question, let me point out that the question relates to the use of the internal temperature sensor, accessible via SI14. The snap-in module is not being used to measure temperature.

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FWIW I powered one up on the desk with no addtional housing, just the PLC as shipped. Ambient is around 20-22degrees and the reported temp on SI14 rose to about 28degrees. So the offset from ambient is not unexpected, but the large variation is less easy to explain.

My reference is an old V120-12-UN2 with a thermocouple attached.

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