Parker
Hannifin
ACR9030 and ACR9040 Utilization of EPL
The ACR9030 and ACR9040 use an EPL network card to control EPL drives
(EPLD). The EPL network is an alternative to the DACs, encoders,
connectors, and cabling associated with the traditional interface drives, as in
the case of the ACR9040, or it may be used in combination with them, as
with the ACR9030. EPL nodes are represented via parameters in the
ACR9030 and ACR9040 as objects (EPLDs) to be attached to an axis, just
as the ENC and DAC objects are. They range from EPLD0 to EPLD15. A
complete description of the network with EPLD parameters and the use of
the
ATTACH EPLD
command are given later in this appendix.
ACR9030 and ACR9040 as Managing Node
The ACR9030 or ACR9040 is the managing node (MN) and the drives are
the controlled nodes (CN). The ACR9030 and ACR9040 will support up to 16
axes total. In the case of the ACR9030, some or all of the axes may be EPL
nodes, and a maximum of 8 may be traditional axes. The ACR9030 and
ACR9040 only support EPL nodes that adhere to device profile DSP-402.
EPL vs. Traditional Drive Interface
A traditional drive interface on an ACR9000 or ACR9030 controller is
contained on the drive connector. It consists of the DAC (or step and
direction) signals out, the encoder feedback in, the drive enable and reset
outputs, and the drive fault input. The position loop is closed in the controller,
meaning the commanded and actual positions of an axis are combined to
result in a torque command to the DAC.
In an EPL drive interface, the position loop is closed in the drive. There is
one EPL cycle synchronized with every ACR9030 and ACR9040 trajectory
period, so the EPL cycle time is automatically established with the
PERIOD
command.
For every EPL cycle, the drive receives the current commanded position, the
current commanded velocity, the current commanded digital outputs, and the
state of what would have been the drive enable and drive reset outputs of
traditional interfaces. See Figure 42. The drive closes its own position loop,
controlling torque by directly controlling current to the motor. Also, for every
EPL cycle, the drive sends the current actual position, the current digital
inputs, the following error, the torque output, and the state of what would
have been the drive fault input of traditional interfaces.
The ACR9030 and ACR9040 generate position set points, and drive enable
and drive reset output states for an EPL axis in exactly the same way it does
for a traditional axis. This means drive I/O commands, jogging, gearing,
cams, and all moves can be used with an EPL axis. Similarly, the ACR9030
and ACR9040 respond to drive fault input states exactly the same way it
does for a traditional axis. The ACR9030 and ACR9040 only use the
feedback information from the drive to update the actual position, following
error, and output signal axis parameters.
168 ACR9000 Series Hardware Installation Guide
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