Name: Control Techniques unidrive sp
Brand: Control Techniques
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74 Unidrive SP Advanced User Guide

www.controltechniques.com Issue Number: 7

If any other command is used then the response is as follows (encoder to drive).

Example of EnDat transfer: Read position

Disable drive encoder position check by setting Pr 90.21 to one. This should be set back to zero at the end of the transfer if encoder position checking

is required.

Transfer the "read position" message to the encoder comms buffer by writing the sequence of words shown in the table below to Pr 90.22. A check

should be carried out before each word is written to ensure that the parameter is zero (i.e. the drive has taken any previous data).

The second word contains the address which is not required for the command, but has been passed to the drive so that a word with bit 14 set to one

is received by the drive to initiate the data transfer to the encoder. When the encoder response has been received by the drive the first byte of the

message will be placed in the least significant byte of Pr 90.23 and bit 15 will be set to one. This data should be read and the parameter cleared so

that the drive will put the next byte into this parameter. The sequence of data that could appear in Pr 90.23 for an encoder with 12 turns bits and 13

position bits is shown in the table below.

Turns = 0111 0100 0100 = 0x744

Position = 1 1101 0011 1110 = 0x1d3e

Alarm bit = 0

Example of EnDat transfer: Encoder send parameter

Data written to Pr 90.22

Data read from Pr 90.23

The data is the parameter at address zero is 0x1234.

Address

byte

Data (LSB)

Data (MSB)