The deployment of a wireless control system must cope with a number of effects usually negligible in a wired scenario. To this aim, an experimental analysis on suitable prototypes and testbeds can readably offer a valid and rapid method to forecast the behavior of a real network. In this paper, performance measurement of industrial wireless sensor network in the presence of various type of interference is provided. In particular a Bluetooth, WiFi and Zigbee disturbing network impairs a suitable testbed employing IEEE 802.15.4 wireless sensor nodes. The purpose is to optimize the effectiveness of the medium access control mechanism through the choice of a proper mode of use. The analysis will show that from the measurement of certain parameters (number of failed pollings, experimental cycle-time, and alarm latency) interference effects can be effectively recognized and the network setup optimized.