A process measurement instrument adapted for wireless communication, comprising a measurement unit (7) arranged to determine a measurement value of a process variable, a memory (21) arranged to store a current measurement value of the process variable, a wireless communication unit (8), arranged to access the current measurement value and communicate the current measurement value over a wireless communication channel according to a protocol with intermittently active communication, and arbitration logic (22), in communication with the measurement unit and the wireless communication unit, and arranged to ensure that active periods of the measurement unit occur when the wireless communication is inactive.The measurement unit and communication unit are thus able to share information via the common memory, e.g. by sequential read/write access. This avoids the need for simultaneous activity. The invention can be especially advantageous when the instrument is powered by an internal power store, such as a battery, and extend the lifetime of such a power store.