Delta MMC120 - Manual (Page 43)

MMC120 Linear Motion Control Module Motion Control Parameters
Delta Computer Systems, Inc. 360/254-8688 43
For example, to detect when an axis' target position has come to a halt after an "H" command, monitor for the
following status bit combination:
Halt bit ON (1) (Bit 14)
State bit A OFF (0) (Bit 12)
State bit B OFF (0) (Bit 11)
You may also want to monitor the Stopped bit (bit 15).
As another example, to detect when an internal error has caused a Hard Stop or a transducer error has caused
a Soft Stop, monitor for the following status bits:
Halt bit ON (1) (Bit 14)
Open Loop bit ON (1) (Bit 13)
Bit 13 - Open Loop
This bit is set when the axis is in Open Loop. The axis can be in Open Loop because of an "O" command or
because an error caused a Hard Stop.
NOTE: While an axis is in Open Loop mode it may drift due to a valve 'out-of-null' condition.
Bit 14 - Halt
There are three conditions that will set this bit:
•
A Halt ("H") command is issued
•
An internal error causes a Soft Stop
•
An internal error causes a Hard Stop
This bit is cleared when a new command is issued.
Bit 15 - Stopped
This bit is set when the average speed of the axis is less than 500 Transducer Counts per second and is cleared
when the speed is greater than 1000 Transducer Counts per second. It can be used as an axis obstruction
indication. The Stopped bit is not latched.
Bit 16 - In Position
This bit will be set when the difference between the ACTUAL POSITION and COMMAND POSITION is less
than the value in the IN POSITION field; it is not latched. See the IN POSITION parameter.
NOTE: When bit 16 is set, an axis is at the commanded position. This bit can be monitored by the ladder program
to determine when an axis has arrived at the commanded position.
COMMAND POSITION
The COMMAND POSITION is the requested position (specified by the COMMAND VALUE) with bounds
checking applied. If the requested position is outside the RETRACT or EXTEND LIMIT, the COMMAND
POSITION will be set to the value of the limit, and the axis will go only to the limit. The COMMAND
POSITION is updated when a 'Go', 'Go Using Profile', or 'P' command is issued using the COMMAND
parameter.
TARGET POSITION
The TARGET POSITION is the position calculated by the target generator, using the ACCEL, DECEL,
SPEED, COMMAND VALUE, and MODE parameters, showing where the axis should be at any moment.