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I had set the P79=8 and tried to switch using X16 but there is no switching i.e drive remains in communication.

I am using 20nos. S500 AC drive and writing frequency through Rs485 Communication. My parameters are P.79 =0 n8 =1, inverter starts/stops from external terminals n9 =0, Frequency write via communication n10=1, Communication start Since the drive is in communication it always accepts frequency from communication, now in any case if computer communication cable fails, an auto/manual switch is moved to manual and drive should take frequency from internal POT or through external terminals. I have read the FRS500 Detailed instruction manual and found nothing about switching a mode. However i have attached a page of manual where it says if p79=0 & n10 =1, Computer link is Disabled when PU is selected &Enabled when external is selected, but there it is not mentioned that how to select PU or External. I have tried with X16 Signal but no results. Since Plant is continuous switch over should be fast. Parameter_Details.pdf

I have already installed the Battery. My purpose of using absolute mode is to fix my home refrence and during power up i should get the current position of servo.

I am using MR-J2S Servo with siemens sinumerik system. MR-J2S is configured in Speed mode and recieves 0 to 10V from ADI4 card of siemens. Same card(ADI4) accepts the encoder pulses from servo drive for detecting servo position. Servo motor is connected to ballscrew and i want to use absolute position mode of servo, So is it possible to use servo in absolute positioning mode when configured under speed mode. If it is not possible then is it possible to read absolute data of MRJ2S through ADI4 when configuring servo in positioning mode.

Thanks a lot Colin I think using PID will be the best solution because it removes offset and adjusting I to large value reduces oscillations. During next visit to my site i try out this. One more question is that is it possible to change the values of PID loop(such as Ts, P, I &D) while loop is running.

For example consider that pipe is at ambient temperature and set point is changed to 900Deg. Celsius, So the MV will apply a large correction to heating coil to increase the pipe temperature. Now as the pipe is passing through coil at some linear speed it takes some time for the heated portion of pipe to come in front of pyrometer and this time is dead time. Since MV applies large power to coil to achieve 900Cel., the temperature of pipe doesn't go directly to 900 Cel., the time taken to reach 63% of (900 cel. -ambient temp.) is called lag time

The time taken by the process to respond to any changes in control variable is called DEAD time whereas the time taken by proces to reach 63% of the output when a step input is applied is called lag time

I am working on induction furnace where dead time is very large(approx. 20Sec.) since the pipe to be heated is passed between a round coil for induction heating and the pyrometer for temp. sensing is kept outside coil. However the lag time is very small. Temp. of the pipe is to be kept constant and the output power to coil is controlled to change the temp. of the pipe. I have tried to tune the PID inside FX1N PLC but i am getting too much oscillations. How to tune such PID loops where dead time is too long?

I am using plsy instruction in my application as follows M/c start ------||-------[plsy d36 d38 y0]-- D36 register recieves value from 0 to 5000 from external pot(interfaced to analog input) where as d38 is always kept 0 for speed operation of servo. Whenever i turns my pot to zero(i.e d36 becomes 0) and then to higher value(say d36=200) my plsy instruction doesn't work(i.e no output at y0). However when i switch off my machine start signal and again on everything works fine. What's the problem?

I am attaching application details with diagrams Application_Details.pdf

In my application, it's not possible to put a contact in series with high speed counter. Is there any other alternative?

Its necessary to use c237, so what is the solution? I think i have to switch over to proportional control mode of servo whenever servo is at rest.

Counter(c237 when misoperating) is counting at fast rates i.e 5 or 10 pulses/sec, and also my output servo encoder pulses are set to 1000pulses/rev. So i think this is not because of servo lock. Earlier i had grounded shieled at one end but later because of these problem i tied both ends to GND.

I am using c238 counter(at input X3) to count total no. pulses from 360ppr encoder. Another counter C251(Bi phase counter at x0 & X1) is used to count servo feedback pulse from MRE Servo encoder for position feedback. Input X0 is tied to X2 which is used to count total no. of pulses from servo encoder using C237. Sometimes counter C237 starts to counts even when machine is in stop condition (Servo is in lock condition). Control wires are shielded and shieldings are grounded at each ends. I am not able to understand that this is because of noise or any hardware fault. *(s/s is connected to 24VDC)

Rated speed of motor is 1500rpm(50Hz) and max speed required is also 1500rpm(50Hz). Min speed required to be 150rpm(5Hz)