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TMCM-102 Manual (V1.01 / 7 November 2007) 12

5.5 Encoder interface

The TMCM-102 provides an interface for single ended incremental encoders with TTL (5V) outputs. Use

the encoder entrances A+ for A, B+ for B and (optional) N+ for N. Leave the others unconnected. The

encoder counter can be read by software and can be used to control the exact positioning of the

motor. This also makes closed loop operation possible. The +5V DC supply voltage can be used for the

encoder. For greater orders differential encoders are supported on request, also.

The Encoder channel N is for nulling of the encoder counter. It can be selected as high or as low

active, and it is automatically checked in parallel to the Encoder channel A and B inputs, to give an

exact reference. It has to be determined by the user, which potential of the encoder A and B inputs

correspond to the zero position. This depends on the actual encoder type used.

To read out or to change the position value of the encoder, axis parameter #209 is used. So, to read

out the position of encoder 0 (the only one) use GAP 209, 0. The position values can also be changed

using command SAP 209, 0, <n> , with n = ± 0,1,2,…

To change the encoder settings of an encoder, axis parameter #210 is used:

Please note that the pre-scaler values can only be set and not read back or stored to EEPROM (it has

to be initialized after every power down). To change the pre-scaler of encoder 0 use SAP 210, 0, .

To select a pre-scaler, the following values can be used for :

Value for

Resulting pre-

scaler

SAP command for motor 0

SAP 210, M0,

Resulting steps per rotation

for a 400 line (1600 quadrate

count) encoder

64 0.125 SAP 210, M0, 64 200

128 0.25 SAP 210, M0, 128 400

256 0.5 SAP 210, M0, 256 800

512 1 SAP 210, M0, 512 1600

1024 2 SAP 210, M0, 1024 3200

2048 4 SAP 210, M0, 2048 6400

4096 8 SAP 210, M0, 4096 12800

8192 16 SAP 210, M0, 8192 25600

16384 32 SAP 210, M0, 16384 51200

32768 64 SAP 210, M0, 32768 102400

Table 5.1: TMCL – Pre-scaler values

Formula for resulting steps per rotation:

StepsPerRotation = LinesOfEncoder * 4 * PreScaler

There are some special functions that can also be configured using these values. To select these

functions just add the following values to :

Adder for

SAP command for motor 0

SAP 210, M0,

1 Encoder Channel A polarity for Null channel event (0=negative, 1=positive)

2 Encoder Channel B polarity for Null channel event (0=negative, 1=positive)

4 Clear encoder with next null channel event

16 Encoder Channel N polarity for encoder clearing (0=negative, 1=positive)

Table 5.2: Special encoder functions

Add up both values from this tables to get the required value for the SAP210 command. The

resulting pre-scaler is Value/512. Other pre-scaler values are possible, also.