mitsu plc with IMS stepper

[Guest mattgrise]

I need to use an FX2N-40A1 plc and an FX2N-1PG to run an IMS stepper drive (dumb drive takes in step and direction- hooks directly to motor) I need to replace a Mitsu servo drive that is currently on there now. Can I simply hook the step drive up where the servo drive is now...if it is in pulse train mode? (how do I find out what mode it is in?) I am very new to PLC's and I need to try to get this done right the first time with out looking like a moron. ANY ADVICE would be greatly appreciated.

[mattgrise]

Also, If you need any clarification, or if more info would help....PLEASE respond and I will update! thanks again

[panic mode]

i don't think (i'm pretty sure of that) it will work without program changes but you could hook it to same outputs (Y0~Y1 or Y0~Y6 depending on model). also you need to check signal levels and polarity. I was using couple steppers that had inputs rated for 5V on a FX1S. can you post plc program?

[Guest Guest_mattgrise]

I dont have the program, sorry. do you know what the signal output of the fx1n-1pg is? (maybe 0-5V pulse train?) I could not find documentation online. If it is just a 0-5V pulse train, would it work with a standard dumb drive? (what do they normally take in?) When you say you were working with steppers that had 5v inputs, do you mean digital inputs, or 5V step and direction? Thanks again for your help.

[Sergei Troizky]

Concerning replacement of servo motor with stepper. This is. actually, a system downgrading with only explanation being the lower cost. The stepper is an open loop positioning system with no position feedback. If your current servo system returns position feedback to the PLC, you will have to create a new one with additional hardware (encoder or similar) or reprogram the PLC in order to eliminate such feedback. Another property of steppers is that an overloaded motor stalls. Also, the acceleration/deceleration capabilities are different from servo motors. Now , concerning the IMS drives. By the way, they are not "dumb". The pulse/direction interface is fully adequate for open loop system. Why duplicate in motor drive the control software functions and double/tripple its cost? Also, IMS steppers with IB10x drives are one of the best value choices in their class. The IMS IB10x stepper drive inputs are optoisolation LEDs with maximum rated current ~10mA. No voltage may be applied to the inputs without current limiting resistors. By the way, the input isolators damage is not covered by the IMS warranty. So, if controlled by 24VDC sourcing output, the 2.2-3K resistor must be present between the PLC output and the drive input. The drive Logic Ground should be connected to the -24VDC. If controlled by sinking output, the same resistor must be used as a pull-up resistor from the drive input to 24VDC. The PLC ouput should be connected directly to the drive input. The drive logic ground must be connected to the -24VDC (PLC COM) via zenner diode (3.3 to 5.6V), in order to compensate the sinking output voltage drop. As far as I remember, the 1PG has sinking output. Another difference with servo drive is necessity of current reduction of the drive when the motor is not moving. This is necessary in order to prevent the drive overheating, since the motor inductive impedance is in reverse proportion with the drive output frequency. You must dedicate and program an output to operate a relay for this function. The relay must connect a resistor between the drive Ground and Current Adjust terminals when the motor does not move. See the drive manual for the resistor value. Another current limiting resistor may be necessary during motor movement, if the motor rated current is lower than the drive's rated output current. Note, that the drive Ground must not be connected with the drive Logic Ground. Some specific rules apply to the IMS stepper drives. These drives are high-frequency carrier chopper amplifier with inductive energy recuperation and operate all the time the drive is enabled, even when the motor is not moving. Never disconnect any motor lead from the drive under power. Power the drive from unstabilized power supply and always provide at least 10000 microFarade capacitor for adequate recuperation with 6" maximum wiring to the drive terminals. Edited April 3, 2005 by Sergei Troizky