Parker Hannifin
home | products | how to buy | support & downloads | literature | search

Click Here to go to new EM&D Knowledge Base (FAQ) site

Known issue with MC_Stop and MC_Home in PAM 1.3.0

There is a known issue in PAM 1.3.0 and PAC firmware 1.3.0 regarding the use of MC_Stop and MC_Home. If MC_Stop is triggered while MC_Home is performing a homing routine on an axis, the axis will come to a stop as expected. However, the Done output on MC_Stop will never transition to TRUE. In addition, the axis will never transition from a state of Stopping to a state of Standstill once motion has ceased.

This makes it difficult to write programs that may trigger MC_Stop during a homing routine since there is no easy way to determine when motion has ceased. Most programs would look at the Done output of MC_Stop for that information.

The only way to get out of the Stopping state once this occurs is to set the bDriveStart and bRegulatorOn inputs on MC_Power to FALSE. Because turning off the power stage of the drive is not a valid transition from Stopping, the axis is forcibly transitioned to Errorstop. From Errorstop, executing an MC_Reset will transition the axis to Disabled. From there, the user can set bRegulatorOn and bDriveStart to TRUE to get the axis back into Standstill.

This is considered a high-priority bug and we are working to fix it in the next release of PAM. This bug was not present in PAM 1.2.1 or PAC firmware 1.2.1. Below is a flowchart showing the series of state transitions caused or required by MC_Stop in PAM 1.3.0 and PAM 1.2.1. For additional information, please contact the Applications Department by phone at 800-358-9068 or by email at


06JUN2017 DC