Advice for PLC with Motion

Hello Everyone.

I have a application that I'm working on that will require 3 axis of stepper motion (constant velocity) and 3 PID loops to control a main spindle inverter drive via analog.

I've been using an AB Micrologix 850 (2080-LC50-48QBB) and have had issues with real numbers. The software/hardware has "hijacked" 2 of my variables and puts in very small numbers (1.xxx * 10^-36) and won't let me change them. Rockwell and my local support cannot explain this issue and recommend using a ControlLogix which would at the very least least double the cost of this project.

I would like advice on any other PLC/PAC that might reliably work for this situation. We are usually AB guys here, but we have used other controllers when cost or physical size was the driving factor. I've looked at Automation Direct Productivity 1000, but cost is basically a wash with the Micro 850 and not sure about their reliability. Also looking at a TRiPLC, but have no experience with them. They would effectively reduce the cost by about 40-45%

I need the following (per section of the machine - I have 7 sections total)

Ethernet (Modbus TCP/IP)
Serial (RS-485 Modbus RTU)
3 HSC (Not necessarily high speed, but something that can handle 350 PPS)
3 Stepper Motion axes for constant velocity
3 PID loops
3 analog in - 0-5V preferred
4 analog out - 0-10V preferred
28 24VDC Digital In
21 24VDC Digital Out

Thanks in advance.

I don’t believe the 850 was really designed for what you are trying to put it through, but I don’t have a lot of experience with them. The compactlogix have the “ERM” series with full support for motion control. I’ve used unitronics a hand full of time, it was ok, but I only used it on basic projects. They have servo drives as well.

Whoever you choose I would recommend sticking with plc/drive as the same manufacturer, things are typically a lot less of a headache that way.

I would also recommend the CompactLogix ERM models. For example this one with built in IO I have used before:

1769-L27ERM-QBFC1B Retail ~$4000
CompactLogix 5370 L2 Controller, 2 EtherNet/IP Ports with Device Level Ring Capability, 1MB Memory, 16 DC Inputs, 16 DC Outputs, 4 Universal Analog Inputs, 2 Analog Outputs, 4 High Speed Counters, Up To 4 1769 I/O Expansion Modules, 4 CIP Motion Axis With Kinematics Function, 16 EtherNet/IP and 120 TCP Connections, 24V DC Embedded Power Supply, With 1GB SD Card, Can Support Up To 2GB SD Card, 1 USB Port.

If you don't need direction control, the Siemens S7-1200 can control 4x stepper motors via it's on board PTO outputs, if you need direction control then it can control 2 and you will need another signal board for the 3rd.

You don't need a ERM CLX, thats overkill for stepper control.

Some info here:

https://automationtop.com/control-o...-s7-1200-configuration-of-the-motion-control/

janner_10 said:

If you don't need direction control, the Siemens S7-1200 can control 4x stepper motors via it's on board PTO outputs, if you need direction control then it can control 2 and you will need another signal board for the 3rd.

You don't need a ERM CLX, thats overkill for stepper control.

Some info here:

https://automationtop.com/control-o...-s7-1200-configuration-of-the-motion-control/

Click to expand...

I second Siemens too.
Simple s7-1200 dcdcdc and AI Ao expansion plus modbus 485 communication card should do the trick.
Use the integrated multiprotocol fIeldbus functionality to make most of profinet / Ethernet /tcp/ip functionality.

The AutomationDirect BRX line would do what you want.

https://www.automationdirect.com/ad...kable)/brx_series_plcs_(stackable_micro_brick)

Series B MicroLogix 1400 has on-board all of the mentioned: 3 HSC, 3 axes PTO, PID, Modbus RTU and Modbus TCP.
It also features 4AI/2AO. For more analog it will just need proper extension module(s).
If you are a Rockwell guy, why look for something else?
https://theautomationblog.com/which-allen-bradley-micrologix-plc-models-support-modbus/

All is also doable with CompactLogix, but more complicated and expensive way than on ML1400.

BTW, I wonder what is a spindle that requires 3-loop PID control?

Thanks for the info. I'll look into the ML1400, BRX and 1200.

I don't actually need stepper direction control (But it the future it may need required) But it is always one way or the other not switching. Could possibly switch the motor leads through a Relay or just use a DO to switch it on the drive.

It's not one spindle with 3 loops. It 3 spindles, basically independent machines but all doing the same thing. Currently we have 36 heads on this machine, each has a spindle, a stepper and currently a 7 segment display (which I would like to replace with a Modbus RTU LCD or LED - no space for a 4.3" display)