Firmware version 4.15 solves a problem in version 4.14 where the 875CR measurement may randomly become unstable for 2 second durations. The instability may amount to as much as full scale error in absolute, temperature, or final measurement in some instances. These instabilities when they occur affect the analog outputs, and may cause the 875CR alarms to trigger falsely.
You may view your current firmware version number under the 875CR "STATUS" mode as described in MI 611- 222, Table 7.
If you currently have an 875CR running version 4.14, Foxboro strongly recommends that you upgrade to version 4.15 (or later).
Version 4.15 may be installed using the 875 Upgrade Utility, part number BS811FN available from the Foxboro Company - Invensys Process Systems. If you already have the upgrade utility, then you may download file CR0415.ZIP from the internet, unzip it, and install it using your existing upgrade utility program. For step by step instructions, refer to MI 611-228.
In lieu of using this field upgrade
procedure you may elect to return your 875CR to the factory for upgrade.
To arrange for factory upgrade contact Foxboro’s
If you currently have an 875CR running a firmware version starting with 4, but lower than 4.14, then your 875CR is not subject to the measurement instability, and no action is required. However, you may choose to load version 4.15 to obtain the latest feature set including enhanced immunity to electro-static discharge (ESD).