This chapter describes some of the more common settings that users want to change when setting up EMC2. Because of the various possibilities of configuring EMC2, it is very hard to document them all, and keep this document relatively short.
The most common EMC2 usage (as reported by our users) is for stepper based systems. These systems are using stepper motors with drives that accept step & direction signals.
It is one of the simpler setups, because the motors run open-loop (no feedback comes back from the motors), yet the system needs to be configured properly so the motors don't stall or lose steps.
Most of this chapter is based on the sample config released along with EMC2. The config is called stepper, and usually it is found in /etc/emc2/sample-configs/stepper.
With software step generation, the maximum step rate is one step per two BASE_PERIODs for step-and-direction output. The maximum requested step rate is the product of an axis's MAX_VELOCITY and its INPUT_SCALE. If the requested step rate is not attainable, following errors will occur, particularly during fast jogs and G0 moves.
If your stepper driver can accept quadrature input, use this mode. With a quadrature signal, one step is possible for each BASE_PERIOD, doubling the maximum step rate.
The other remedies are to decrease one or more of: the BASE_PERIOD (setting this too low will cause the machine to become unresponsive or even lock up), the INPUT_SCALE (if you can select different step sizes on your stepper driver, change pulley ratios, or leadscrew pitch), or the MAX_VELOCITY and STEPGEN_MAXVEL.
If no valid combination of BASE_PERIOD, INPUT_SCALE, and MAX_VELOCITY is acceptable, then hardware step generation (such as with the emc2-supported Universal Stepper Controller)
One of the majour flaws in EMC was that you couldn't specify the pinout
without recompiling the source code. EMC2 is far more flexible, and
now (thanks to the Hardware Abstraction Layer) you can easily specify
which signal goes where. (read the ![[*]](crossref.png)
section
for more information about the HAL).
As it is described in the HAL Introduction and tutorial, we have signals, pins and parameters inside the HAL.
The ones relevant for our pinout are1.1:
This file contains several HAL commands, and usually looks like this:
# standard pinout config file for 3-axis steppers # using a parport for I/O # # first load the parport driver loadrt hal_parport cfg="0x0378" # # next connect the parport functions to threads # read inputs first addf parport.0.read base-thread 1 # write outputs last addf parport.0.write base-thread -1 # # finally connect physical pins to the signals linksp Xstep => parport.0.pin-03-out linksp Xdir => parport.0.pin-02-out linksp Ystep => parport.0.pin-05-out linksp Ydir => parport.0.pin-04-out linksp Zstep => parport.0.pin-07-out linksp Zdir => parport.0.pin-06-out # create a signal for the estop loopback linkpp iocontrol.0.user-enable-out iocontrol.0.emc-enable-in # create signals for tool loading loopback linkpp iocontrol.0.tool-prepare iocontrol.0.tool-prepared linkpp iocontrol.0.tool-change iocontrol.0.tool-changed # create a signal for "spindle on" newsig spindle-on bit # connect the controller to it linkps motion.spindle-on => spindle-on # connect it to a physical pin linksp spindle-on => parport.0.pin-09-out ### ### You might use something like this to enable chopper drives when machine ON ### the Xen signal is defined in core_stepper.hal ### # linksp Xen => parport.0.pin-01-out ### ### If you want active low for this pin, invert it like this: ### # setp parport.0.pin-01-out-invert 1 ### ### A sample home switch on the X axis (axis 0). make a signal, ### link the incoming parport pin to the signal, then link the signal ### to EMC's axis 0 home switch input pin ### # newsig Xhome bit # linkps parport.0.pin-10-in => Xhome # linksp Xhome => axis.0.home-sw-in ### ### Shared home switches all on one parallel port pin? ### that's ok, hook the same signal to all the axes, but be sure to ### set HOME_IS_SHARED and HOME_SEQUENCE in the ini file. See the ### user manual! ### # newsig homeswitches bit # linkps parport.0.pin-10-in => homeswitches # linksp homeswitches => axis.0.home-sw-in # linksp homeswitches => axis.1.home-sw-in # linksp homeswitches => axis.2.home-sw-in ### ### Sample separate limit switches on the X axis (axis 0) ### # newsig X-neg-limit bit # linkps parport.0.pin-11-in => X-neg-limit # linksp X-neg-limit => axis.0.neg-lim-sw-in # newsig X-pos-limit bit # linkps parport.0.pin-12-in => X-pos-limit # linksp X-pos-limit => axis.0.pos-lim-sw-in ### ### Just like the shared home switches example, you can wire together ### limit switches. Beware if you hit one, EMC will stop but can't tell ### you which switch/axis has faulted. Use caution when recovering from this. ### # newsig Xlimits bit # linkps parport.pin-13-in => Xlimits # linksp Xlimits => axis.0.neg-lim-sw-in # linksp Xlimits => axis.0.pos-lim-sw-in ### ### you can also use the "net" syntax to accomplish the "newsig" and "link" ### operations all at once. This command does the same thing as the above ### block. ### # net Xlimits parport.pin-13-in => axis.0.neg-lim-sw-in axis.0.pos-lim-sw-in
There are a couple of operations that get executed when the standard_pinout.hal gets executed / interpreted:
for details)
If you want to change the standard_pinout.hal file, all you need is a text editor. Open the file and locate the parts you want to change.
If you want for example to change the pin for the X-axis Step & Directions signals, all you need to do is to change the number in the 'parport.0.pin-XX-out' name:
Hint: make sure you don't have more than one signal connected to the same pin.
If external hardware expects an ``active low'' signal, set the corresponding -invert parameter. For instance, to invert the spindle control signal:
If your spindle can be controlled by a PWM signal, use the pwmgen component to create the signal:
Some amplifiers (drives) require an enable signal before they accept and command movement of the motors. For this reason there are already defined signals called 'Xen', 'Yen', 'Zen'.
To connect them use the following example:
As you can see in by default the stepper
configuration assumes no external ESTOP button. 1.4
To add a simple external button you need to replace the line:
for additional information