LM628, LM629

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SNVS781C – JUNE 1999 – REVISED MARCH 2013

Bit 13, the UDF-executed flag, is set to logic one when the UDF command is executed. Because bit 13 is cleared

at the end of the sampling interval in which it has been set, this signal is very short-lived and probably not very

profitable for monitoring.

Bit 12, the forward direction flag, is meaningful only when the LM628 is in velocity mode. The bit is set to logic

one to indicate that the desired direction of motion is “forward”; zero indicates “reverse” direction. Bit 12 is set

and cleared via command LTRJ. The actual setting and clearing of bit 12 does not occur until command STT is

executed.

Bit 11, the velocity mode flag, is set to logic one to indicate that the user has selected (via command LTRJ)

velocity mode. Bit 11 is cleared when position mode is selected (via command LTRJ). The actual setting and

clearing of bit 11 does not occur until command STT is executed.

Bit 10, the on-target flag, is set to logic one when the trajectory generator has completed its functions for the last-

issued STT command. Bit 10 is cleared by the next STT command.

Bit 9, the turn-off on-error flag, is set to logic one when command LPES is executed. Bit 9 is cleared by

command LPEI.

Bit 8, the 8-bit output flag, is set to logic one when the LM628 is reset, or when command PORT8 is executed.

Bit 8 is cleared by command PORT12.

Bits 0 through 7 replicate the status byte (see Table 7), with the exception of bit 0. Bit 0, the acquire next index

flag, is set to logic one when command SIP is executed; it then remains set until the next index pulse occurs.

RDIP COMMAND: READ INDEX POSITION

Command Code: 09 Hex

Bytes Read: Four

Data Range: C0000000 to 3FFFFFFF Hex

Executable During Motion: Yes

This command reads the position recorded in the index register. Reading the index register can be part of a

system error checking scheme. Whenever the SIP command is executed, the new index position minus the old

index position, divided by the incremental encoder resolution (encoder lines times four), should always be an

integral number. The RDIP command facilitates acquiring these data for host-based calculations. The command

can also be used to identify/verify home or some other special position. The bytes are read in most-to-least

significant order.

RDDP COMMAND: READ DESIRED POSITION

Command Code: 08 Hex

Bytes Read: Four

Data Range: C0000000 to 3FFFFFFF Hex

Executable During Motion: Yes

This command reads the instantaneous desired (current temporal ) position output of the profile generator. This

is the “setpoint” input to the position-loop summing junction. The bytes are read in most-to-least significant order.

RDRP COMMAND: READ REAL POSITION

Command Code: 0A Hex

Bytes Read: Four

Data Range: C0000000 to 3FFFFFFF Hex

Executable During Motion: Yes

This command reads the current actual position of the motor. This is the feedback input to the loop summing

junction. The bytes are read in most-to-least significant order.

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Product Folder Links: LM628 LM629