Delta MMC120 User Manual download pdf (Page 41)

MMC120 Linear Motion Control Module Motion Control Parameters

Delta Computer Systems, Inc. 360/254-8688 41

Readback Parameters

ACTUAL POSITION

The ACTUAL POSITION is the measured position of the axis at any moment. This position is updated every

millisecond. The ACTUAL POSITION is calculated from the TRANSDUCER COUNTS as follows:

TRANSDUCER COUNTS x SCALE

ACTUAL POSITION =  + OFFSET

32768

AXIS STATUS Word (See map on page 42)

The axis STATUS word contains 16 bits of information about the condition of the axis. You can use any of

the first eight error bits to trigger a STOP on the axis. (See the AUTO STOP parameter on page 31.)

Error bits 2 through 8 are cleared whenever a 'G' command is given.

NOTE: Bit 1 is the MSB, Bit 16 is the LSB.

Bit 1 - No Transducer

This bit is set and the corresponding front panel axis LED (light emitting diode) glows red if the transducer

does not respond at least once every 6 milliseconds. It causes a Hard Stop or a Soft Stop, depending on the

setting of AUTO STOP bit 9 (page 31). This bit will stay on until a new command is given to the axis.

Bit 2 - Transducer Noise

If a new transducer count differs from the previous reading by more than 250 counts, the new value is assumed

to be an error and this error bit is set. When the Transducer Noise bit is set, the system response depends on

the setting of the AUTO STOP word. It causes a Hard Stop or a Soft Stop, depending on the setting of AUTO

STOP bit 10. This bit will stay on until a new command is given to the axis.

Bit 3 - Transducer Overflow

This bit is set when there has been no stop pulse from the transducer by the time the counter has overflowed 18

bits (about 2 ms). When this bit is set, the system response depends on the setting of the AUTO STOP word. It

causes a Hard Stop or a Soft Stop, depending on the setting of AUTO STOP bit 11. This bit will stay on until

a new command is given to the axis.

Bit 4 - Overdrive

This bit is set when the calculated drive output exceeds the 12 bit range of the D/A converter. Usually this

error indicates the system does not have enough power to drive the axis at the requested SPEED. The module

will truncate the drive to 12 bits. It causes no action, a Soft Stop, or a Hard Stop, depending on the setting of

AUTO STOP bits 4 and 12. This bit will stay on until a new command is given to the axis.

BIT 5 - Parameter Error

This bit is set when an initialization parameter or control parameter is out of bounds. In some cases one

parameter's limit will depend on the value of another parameter, so definite limits may not always be available.

However, the motion controller does try to replace the erroneous value with another that is within range, so the

offending parameter can be determined by comparing the parameter values before and after the error bit is set.

This error causes no action, a Soft Stop, or a Hard Stop, depending on the setting of AUTO STOP bits 5 and

13. This bit will stay on until a new command is given to the axis.

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Delta MMC120 User Manual Page 41