UPDATE: The bug described in this article has been fixed in PAM 1.4.0. (please note that PAC firmware 1.4.0 is required in order to use PAM 1.4.0). Users are advised to use the latest version of PAM and PAC firmware for any new application. The latest version of PAM and PAC firmware can be downloaded on the PAC product page here.
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 email@example.com.