Reversion of rotation

With an encoder, the counting direction is determined by the phase position of the signals on tracks A and B.

Forward (cw): Signal on track A leads track B by 90°
Reverse (ccw): Signal on track A lags track B by 90°

To adapt the counting direction to the application, this logic can be inverted by setting the bit in index 0x80n0:0E “Reversion of rotation”.

Reversion of rotation 1: — Fig.35: Reversion of counting direction (Index 0x80n0:0E “Reversion of rotation”) for an encoder

With a counter/pulse generator the counting direction is determined by the level at track B.

Forward (cw): LOW level at track B or input open
Reverse (ccw): HIGH level at track B

Setting the bit in index 0x80n0:0E “Reversion of rotation” also inverts the logic of the counting direction. An overview of the resulting counting direction is shown in the following table.

The current level at input B is displayed via process data “Status of input B” (0x60n0:0A).

Reversion of rotation 2: — Fig.36: Reversion of counting direction (Index 0x80n0:0E “Reversion of rotation”) for a counter/pulse generator

0x80n1:1D “Counter mode”	Level at input track B	0x80n0:0E “Reversion of rotation”	Resulting counting direction
1: Counter RS422 (diff. input)	Input open / LOW level	FALSE	positive
	Input open / LOW level	TRUE	negative
	RS422 signal level	FALSE	negative
	RS422 signal level	TRUE	positive
3: Counter TTL (single ended)	Input open / LOW level, voltage level < 0.8 V	FALSE	positive
	Input open / LOW level, voltage level < 0.8 V	TRUE	negative
	TTL voltage level 2.0 V to 6.0 V, with min. 2.1 mA current	FALSE	negative
	TTL voltage level 2.0 V to 6.0 V, with min. 2.1 mA current	TRUE	positive
5: Counter open collector	Input open / LOW level, voltage level < 0.8 V	FALSE	positive
	Input open / LOW level, voltage level < 0.8 V	TRUE	negative
	Open collector voltage level 2.0 V to 6.0 V, with min. 2.1 mA current	FALSE	negative
		TRUE	positive

	Status LED input B as counter RS422 (diff. input) If the input of track B is open in counter mode “RS422 (diff. input)”, a broken wire is detected and the status LED of input B lights up red. The error detection and indication via the LED can be deactivated via index 0x80n0:0C “Error detection B”.