Is it possible to make 1734 VHSC24 slave to kinetic 5700 drives

Hey people!

For a school project, I and a friend have a 1734-VHSC24 connected to an encoder.
Simultaneously we have 2 x kinetix 5700 with servo motors which already is running with a MAG gear condition.
We would like to make the encoder a master and the 2 drives slaves for the encoder. Everything is connected and running, but we are new to servo control and unsure how to write a suiting code. We tried to move the encoders PresentData to the "position" of one of the two axis in a motion axis move (MAM) block, but even though the value of the encoder presentdata is shown, the slave doesn't seem to follow. Do any of you guys have an idea what to do?

Welcome to the PLCTalk forum community !

This is an excellent illustration of the difference between an embedded local counter device and a device with the capability of participating in a distributed and coordinated motion control system.

Any of the A-B "VHSC" modules, back to the 1771-VHSC in the late 1980's, are designed to control onboard physical outputs based on preset count or speed values.

They are not meant to be part of the motion control subsystem in the ControlLogix. They don't support CIP Motion protocol, or send their position and velocity rapidly to the ControlLogix to allow them to be linked to an Axis object.

In theory you could keep moving the current position of a Counter to the target position of a Motion Axis Move that gets re-triggered frequently, but that is probably going to produce extremely choppy motion as the MAM tries to accelerate and decelerate in a trapezoidal or s-curve profile to hit that target position, which then quickly moves to a new value.

The appropriate way to do a "position follower" is to use an encoder connected to a ControlLogix Motion-capable device. That includes a chassis-mounted module like the old 1756-M02AE, or the auxiliary encoder input channel on a multi-axis servo like the Kinetix 5700, or even an encoder that is built specifically to participate in a CIP Motion system like the 842E-CM.

Do you have any other hardware to use on this system, other than that 1734-VHSC ? Even another low-end servo controller (like a Kinetix 350) that has an encoder input might be able to be used as a Feedback-Only device.

Hi Ken Roach. Thank you for your response.

Unfortunately it is unlikely that our school will allow us to change the hardware of the system. I will ask them if it is possible.

Because it is a school project and the main purpose is to show that we can make one servo master and the two others followers, the master wouldn't necessarily have to be the motor which encoder is connected to the 1734-VHSC24.


The motor with the 1734-VHSC24 module is driven by a Powerflex 40P.
Would it be possible to make the Powerflex 40P follow the velocity of one of the two Kinetix5700 drives?

We are looking at the Powerflex 40P manual but with our limited knowledge on the topic it is hard for us to tell if an additional module is needed for this operation.