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Compact FieldPoint cFP-TC-120 and cFP-CB-3 Product Notification Information

Hardware: Compact FieldPoint>>Analog I/O Modules>>cFP-TC-120, Compact FieldPoint>>Connector Blocks>>cFP-CB-3

Problem:

As noted in our recent product notification letter, National Instruments recently discovered that revision B of the cFP-TC-120 may not meet performance specifications when operating in environments at the extreme ends of the operating temperature range. Furthermore, revisions A and B of the cFP-CB-3 isothermal connector block can introduce an offset of up to 1.1 °C if the connector block is installed next to a heat-producing module or controller. National Instruments requests that you return your cFP-TC-120 and cFP-CB-3 hardware for repair.

Solution:

To find out if your hardware is affected, look at the part number printed on the module or connector block. The revision is the letter in the part number. For example, the revision B cFP-TC-120 has part number 184522B-02. The revision A and revision B cFP-CB-3 connector blocks have part numbers 188998A-01 and 188998B-01 respectively. The current revisions of the cFP-TC-120 and cFP-CB-3 are unaffected by this issue and do not require repair.

The cold-junction (CJ) reading of the revision B cFP-TC-120 has an additional error of up to 1.8 °C or –3.5 °C at the ends of the operating temperature range, as the chart below shows.



The additional CJ error does not have a one-to-one correlation with errors you see in measurements. Below are charts for many common thermocouple types and the additional CJ errors at specific measurement temperatures. These charts are based on the assumption that the ambient temperature of your FieldPoint system is 30.5 °C or 13.4 °C, which results in 0.5 °C of additional error. For example, if your system is operating at a temperature of 40 °C, your measurements have –1 °C of additional CJ error (from the chart above). If you are using a J-type thermocouple and taking measurements at about 800 °C, the measurements have an additional error of 0.8 °C:

1 °C/0.5 °C = 2; 2 × 0.4 °C = 0.8 °C.



Note: Use the Word document entitled TC-120 Graphs attached to this article for a better view of these graphs.

Not all applications are affected by this issue. The following applications will operate properly with the additional error uncorrected:

• Applications in which the ambient temperature of the FieldPoint system is near room temperature and the specific additional error for your thermocouple type and measurement range is acceptable
• Applications that measure relative temperatures or changes in temperature rather than absolute temperature

Additionally, we recently found that the cFP-CB-3 does not meet our isothermal specification when mounted next to a heat-producing I/O module or controller. This can cause offsets of 1.1 °C between channels if the cFP-CB-3 and cFP-TC-120 are next to the controller or another heat-producing I/O module. To fix this problem, we need to add a heat shield to both the cFP-TC-120 and the cFP-CB-3. Therefore, National Instruments is recalling both of these products for rework.

If you have one of the listed revisions of the cFP-TC-120 and/or cFP-CB-3, please call National Instruments at (877) 493-2406 to obtain a service request number and to arrange repair and shipping. National Instruments will repair the affected product(s) at no cost to you.

If you also have an FP-TC-120, a similar issue exists on this module that does not require repair. To get more information on this issue and to download a VI to correct it, please visit the following URL:

Classic FieldPoint FP-TC-120 Product Notification Information

Please accept our apology for the inconvenience. National Instruments is committed to your total satisfaction and to maintaining your confidence in our products. We have re-validated the specifications of these products and corrected their test plans. If you have any questions or concerns, please contact the FieldPoint Product Support Engineer.

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Report Date: 05/27/2005
Last Updated: 08/16/2007
Document ID: 3LQF7TVM

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