AMCI SMD17K, Руководство пользователя

Страница: 14 / 98

SMD17K S
PECIFICATIONS
SMD17K User Manual
ADVANCED MICRO CONTROLS INC.
14
Indexer Functionality (continued)
Synchronizing Moves
By default, the SMD17K products use the SyncManager 2 event to control the transfer of data from the Ether-
CAT Slave Controller (ECS) to the microprocessor that controls motion. This allows the SMD17K to execute
commands as soon as new data arrives. When more than one axis is updated with a single EtherCAT packet,
the time difference between axis update is very short. Updating multiple axes with a single packet allows the
EtherCAT network to out perform the update times of other industrial network protocols.
On very fast machines, or large machines that require more than one transfer to update all axes, the EtherCAT
Distributed Clock (DC) functionality can be used to closely synchronize motion over multiple axes if using
the SyncMaster2 event proves to be ineffective.
The EtherCAT Distributed Clock functionality is built into the ECS used by the SMD17K products. The
SMD17K can act as the reference clock for the system if it is the first device in the EtherCAT network. The
SYNC0 signal, which is based off of the Distributed Clock, can be use to synchronize the start of moves over
multiple devices. The time between when the SYNC0 signal is received by the main processor of the
SMD17K and when the driver begins to cause motion is 520 ± 25 microseconds. The 520 microseconds is
the time required to read the data from the ECS once the SYNC0 signal becomes active. The ±25 microsec-
onds is caused by the 20 kHz update frequency of the PWM drivers.
For the SMD17K, the minimum update time on the SYNC0 signal is two milliseconds. If the task time is less
than two milliseconds, the SYNC0 time must be a multiple of the task time.
Stall Detection with SMD17K Units
Stall Detection is one of the additional features available to you when you order an encoder option on an
SMD17K. When Stall Detection is enabled, the SMD17K monitors the encoder for position changes, regard-
less of whether or not a move is in progress. If the error between the encoder position and the motor position
exceeds forty-five degrees, the SMD17K responds in the following manner:

The stall is reported in the network input data.

The motor position becomes invalid. (The machine must be homed or the motor position preset before
Absolute moves can be run again.

If a move was in progress, the move is stopped.
Note that a move does not have to be in progress for stall detection to be useful. By enabling stall detection,
the SMD17K can notify the system if the motor shaft moves more than forty-five degrees while power is
removed from the motor. This may occur when the motor must hold a load against gravity or other external
forces affect the load when power is removed.
As described later in this chapter, there is an auxiliary power pin that powers the electronics of an SMD17K
but does not power the motor. The primary use of this feature is to keep the unit on the network while power
is removed from the motor. When using the DCPower
AUX
pin, the SMD17K cannot sense when power has
been removed from the DCPower
MAIN
pin. Stall detect can be used in these cases as well. If motion is com-
manded and a stall detection event occurs immediately, it is likely that the main power has been removed
from the motor and the SMD17K is running on DCPower
AUX
power only.