Abnormal number of servo receiving command pulses

Phenomenon: When the R8 servo is paired with Samkoon PLC or third-party PLC or control board , it is common to see pulse type of servo receive inaccurate numbers of pulses.

terms of settlement:

1. The command pulse frequency is too high, exceeding the maximum servo pulse receiving frequency; The maximum pulse frequency for the 24V collector input of the R8 servo pulse input is 200KHZ, and the maximum pulse frequency for the 5V differential input is 500KHZ. When the command pulse frequency is too high, the number of pulses received by the servo will be a little small. At the customer site, it is possible to try reducing the operating speed of the equipment and lowering the command pulse frequency by checking the P13-12 parameter (command pulse count) on the servo digital tube panel to confirm its effectiveness; If the number of pulses received by the servo is accurate after reducing the command pulse frequency, the number of pulses per cycle P05-00 can be reduced (pulse equivalent increases) without affecting the accuracy, and the PLC's single cycle pulse parameter can be modified to solve this problem; If reducing the command pulse frequency is ineffective, you can continue to troubleshoot according to point 2.

2. The wiring of the equipment is poor, causing significant interference and affecting the quality of the pulse signal; Due to the layout and wiring of the electrical cabinet not necessarily ensuring sufficient isolation of strong and weak electricity, and the unreasonable wiring of the 24V power supply and 0V distribution, the quality of the pulse signal may be poor, and there may be multiple pulses or pulse loss. At the customer's site, the accuracy of the number of pulses received by the servo can be confirmed by disabling the other nearby servos; If the number of pulses received after the other servo is disabled is accurate, the P05-18 (pulse signal filtering)/P05-19 (direction signal filtering) servo parameters can be increased (it is recommended to set P05-19/P05-19 the same), and the filtering time of the pulse and direction signals can be increased to confirm whether it is effective (the maximum value of the parameter is 255, the filtering time is about 2.5us, and the filtering effect is limited); A better solution is to confirm whether the command pulse wiring is too close to the strong current wiring (maintaining a distance of more than 30cm), whether it shares a 24V power supply with the servo motor brake (using a separate switch power supply to supply power to the command pulse), whether the PE wire on the servo command pulse wire is connected to the iron shell of the CN1 DB44 terminal on the servo side (disconnect the iron shell of the R8 servo CN1 DB44 terminal from the PE wire of the pulse wire), and adjust and optimize the command pulse wiring. When the command pulse frequency is low, the signal width of the pulse is relatively large and generally not easily affected by interference. If it can be ruled out that the abnormal pulse counting is caused by interference, continue to investigate according to point 3. Typical scene: The 2.5M long command control line, 24V power line, and PULS -/IGN - are routed separately, small impact on pulse signals resulting in a large current loop area but may big impact on directional signals, leading to inaccurate judge of a reverse signal.

3. The phase of the pulse and direction signal sent by the third-party PLC or control board does not meet the requirements; When using the direction+pulse mode, if the output direction signal delay is large, it will cause some reverse pulses to be error counted as forward pulses, ultimately resulting in a phenomenon of even numbered pulse counting deviation. At the customer site, the influence of pulse reception can be eliminated by modifying the program or disconnecting the directional signal wiring; If the servo receives an accurate number of pulses after disconnecting the direction signal wiring, it is highly likely that the abnormal command pulse count is caused by the direction signal. If the pulse counting deviation is 2 after a reciprocating operation, it can be solved by modifying P05-17 (command pulse signal reverse) to 1

(typical example: third-party control board); If the pulse counting deviation is an even number greater than 2 after a reciprocating operation, it is necessary to modify the delay relationship between the pulse and direction signals on the PLC side to solve the problem.

(Typical example: third-party PLC+extended IO module. The low-speed IO port output direction signal of the extended module has a large time delay, resulting in a large even pulse deviation during reciprocating operation.)

4. If none of the above solutions solve the problem of abnormal pulse reception, it is possible that the driver is damaged and can be replaced a new one for testing and confirmation.