Synchronizing method for communication

A synchronization control system which comprises a first machine which is the master and a second machine which is connected to the first machine as a slave;

• wherein
• said first machine has
• a transmission means for transmitting a specific signal to the second machine;
• a reception means for receiving from the second machine an answer signal to the effect that the second machine has received the specific signal;
• and
• a first timer which begins measuring when said means of transmission transmits said specific signal, and finishes measuring when said means of reception receives from the second machine the answer signal to the effect that it has received said specific signal,
• wherein said second machine has
• means for transmitting back an answer signal to the first machine as soon as it receives said specific signal from the first machine, and
• a second timer for the purpose of adjusting the time from the request for transmission from the first machine until sampling of the signal to the first machine in response to the request,
• further said synchronization control system has
• means for calculating propagation delay time, whereby the propagation delay time between said first machine and said second machine is calculated from the measured time of said first timer;
• and
• means for programming the value calculated by said calculating propagation delay time calculating means as one correction value of the second timer of the second machine.

A serial communication system between a numerical control device and servoamplifiers which comprises one numerical control device and a plurality of servoamplifiers connected in the manner of a daisy-chain to that numerical control device, said numerical control device sending a synchronizing signal to each of the servoamplifiers by way of a transmission line in order to implement synchronized control with the servoamplifiers, wherein:

• said servoamplifiers have
• a reception control circuit which receives signals sent from said numerical control device,
• a timer which begins measuring when said reception control device receives a signal from said numerical control device, and
• a transmission control circuit which sends feedback data from pulse coders attached to the servo motor and servo motors downstream from it when the timer has finished measuring,
• further said timers
• connect a means whereby a value obtained by subtracting the time required for the signal to propagate on the transmission line from the time required from the output of the signal for starting calculation of the command voltage within said numerical control device until the reception of the signal by the timer from said reception control circuit is set as a first correction value, and a means whereby the time required for the signal to propagate on the transmission line is set as a second correction value, and,
• finish measuring concluding when the amount of time obtained by subtracting the total of said first and second correction values from the time which has elapsed from a point in time which is pre-determined as the point at which feedback data from the pulse coder linked to the servo motor is read, and the signal for starting calculation of the command voltage was output within said numerical control device.

A serial communication system between a numerical control device and servoamplifiers which comprises one numerical control device and a plurality of servoamplifiers connected in the manner of a daisy-chain to that numerical control device, said numerical control device sending a synchronizing signal to each of the servoamplifiers by way of a transmission line in order to implement synchronized control with the servoamplifiers, wherein

• said numerical control device includes
• a reception control circuit for the purpose of receiving output signals from the servoamplifier furthest upstream,
• a transmission control circuit for the purpose of transmitting the delay time measurement packet,
• a first timer which begins measurement with the transmission of said delay time measurement packet, and finishes measurement when said reception control circuit receives the delay time measurement packet sent back from the servoamplifier furthest upstream,
• a first delay time calculating means whereby the propagation delay time on the transmission line between this numerical control device and the servoamplifier furthest upstream is calculated on the basis of the value measured by said first timer;
• and
• means for setting the propagation delay time calculated by said first delay time calculating means as a correction value into the servoamplifier furthest upstream,
• wherein, each of said plurality of servoamplifiers includes
• a reception control circuit for the purpose of receiving the header of the delay time measurement packet by way of the transmission line from said numerical control device where it is the servoamplifier furthest upstream, or otherwise from the servoamplifier next upstream,
• a delay time measurement packet detection circuit which detects the header of the delay time measurement packet sent back from the servoamplifier next downstream,
• a second timer which begins measurement when said reception control circuit receives the header of the delay time measurement packet, and finishes measurement when said delay time measurement packet detection circuit detects the header of the delay time measurement packet which has been sent back,
• a second delay time calculating means whereby the propagation delay time on the transmission line between this servoamplifier and the servoamplifier next downstream is calculated on the basis of the value measured by said second timer, and,
• means for setting the propagation delay time calculated by said second delay time calculating means as a correction value into the servoamplifier next downstream.