Upgrading from ACR8020 to ACR9000 Part 2

DRIVE I/O
The ACR8020 has no concept of an amplifier (a.k.a. 'drives') enabling scheme and assumes that the drives are ready for control as soon as the controller powers up. This is not a Parker-recommended setup as there is no way to for the controller to disable the drive if there is a failure. It is up to the operator to activate the E-stop.

The packaging of the ACR9000 now dedicates some of the digital I/O to the control and monitoring of the servo and stepper drives. Since all of Parker's drives have the ability of disabling the drive via an input we added a whole new set of control and status flags that deal with drive enabling to the ACR9000. These are located in the Quaternary Axis Flags.

To make the ACR9000 as backwards compatible as possible, a control flag can be used to disable this new drive control feature. Clearing the Enable Drive I/O flag allows the ACR9000 to be used in applications that previously used any of the legacy ACR controllers (ACR8000, 1200, 1500, 1505, 2000, 8010, and 8020.) Keep in mind that this will require that all error checking and drive monitoring will have to be handled by the user's AcroBASIC programs. Since this is an upgrade document, this assumes that the user's programs already have this error-checking in place.It is recommended that all of the following drive errors should disable the drive and stop motion:
Encoder errors (Encoder Signal Fault and Encoder Signal Lost flags)
Excess Following Error
Drive Fault Input, if applicable

If the application does not have any of this checking, then it is recommended that the user's programs be modified to make use of the ACR9000 drive I/O feature. This allows issuing a command like DRIVE ON X to perform the drive enable sequence as well as monitor for faults.

MOTION ENABLE INPUT
The ACR9000 has an optically-isolated input that must have 5-24VDC connected to allow the drives to enable and motion to occur. The ACR8020 has nothing that is equivalent so if placing a ACR9000 in an older ACR8020 application, be sure to wire in the DC supply. If it's not desired to change the AcroBASIC programs, just hardwire this input into one of the encoder 5VDC outputs so that power is there any time the controller is powered up.

HOMING AND END-OF-TRAVELS
In the ACR8020, there is no firmware concept of homing or hardware end-of-travels. This is most likely implemented in the user's AcroBASIC programs. These programs will still work for the ACR9000, just change the code to look for the appropriate inputs.