Abstract: This invention relates to a system for monitoring the condition and operation of remotely located machines, such as coin-operated vending machines. In one embodiment, switches in each machine convert operating conditions into a binary digital word for that machine, which is stored temporarily. Such words for a plurality of machines are then transferred to a memory, whence they are retrieved, coded as to machine number and transmitted via telephone line to a control processing unit where the various machine conditions are recorded and displayed.