A monitoring system for a conveyor of articles (100;100(j)), said conveyor of articles comprising a static portion and at least one respective endless transport chain adapted to be moved with respect to the static portion when the conveyor of articles is in operation, said system including: - a reference element located on the transport chain; - a first sensor integral with the static portion and a second sensor integral with the static portion, said first and second sensors being distant to each other by a first distance (Scd), each sensor being configured to sense the passage of the reference element close to the sensor itself during the operation of the conveyor; - counting means (210(j)) coupled with the sensors and configured to measure: a) a first time corresponding to the time elapsed between a first passage of the reference element close to the first sensor and a first passage of the reference element close to the second sensor, and b) a second time corresponding: - to the time elapsed between the first passage of the reference element close to the first sensor and a second passage of the reference element close to the first sensor, or - to the time elapsed between the first passage of the reference element close to the second sensor and a second passage of the reference element close to the second sensor, said second passage being subsequent to the first passage; - computing means (210(j); 340) configured to: c) determining the transport chain movement speed with respect to the static portion based on the first measured time and the first distance, and d) determining the length of the chain based on the determined movement speed and based on the second measured time. - a reference element located on the transport chain; - a first sensor integral with the static portion and a second sensor integral with the static portion, said first and second sensors being distant to each other by a first distance (Scd), each sensor being configured to sense the passage of the reference element close to the sensor itself during the operation of the conveyor; - counting means (210(j)) coupled with the sensors and configured to measure: a) a first time corresponding to the time elapsed between a first passage of the reference element close to the first sensor and a first passage of the reference element close to the second sensor, and b) a second time corresponding: - to the time elapsed between the first passage of the reference element close to the first sensor and a second passage of the reference element close to the first sensor, or - to the time elapsed between the first passage of the reference element close to the second sensor and a second passage of the reference element close to the second sensor, said second passage being subsequent to the first passage; a) a first time corresponding to the time elapsed between a first passage of the reference element close to the first sensor and a first passage of the reference element close to the second sensor, and b) a second time corresponding: - to the time elapsed between the first passage of the reference element close to the first sensor and a second passage of the reference element close to the first sensor, or - to the time elapsed between the first passage of the reference element close to the second sensor and a second passage of the reference element close to the second sensor, said second passage being subsequent to the first passage; - to the time elapsed between the first passage of the reference element close to the first sensor and a second passage of the reference element close to the first sensor, or - to the time elapsed between the first passage of the reference element close to the second sensor and a second passage of the reference element close to the second sensor, said second passage being subsequent to the first passage; - computing means (210(j); 340) configured to: c) determining the transport chain movement speed with respect to the static portion based on the first measured time and the first distance, and d) determining the length of the chain based on the determined movement speed and based on the second measured time. c) determining the transport chain movement speed with respect to the static portion based on the first measured time and the first distance, and d) determining the length of the chain based on the determined movement speed and based on the second measured time.