I/O modules • 237
Incremental-encoder-interface 750-631
Modular I/O System
ETHERNET TCP/IP
cumulation register depending upon the status of the overflow or underflow
bits.
Setting Counter Position:
The counter can be preset with the CNT_SET bit.
The desired preset is loaded into the data register and the CNT_SET bit is set
from 0 to 1. The CNTSET_ACC bit will be set to 1 when the preset value is
loaded into the count register.
Maintaining the Present Counter Position:
The encoder present value may be maintained or latched via the external Latch
input. First the external latch must be enabled via the EN_LATEXT bit. Once
the input is enabled, the data will be latched into the counter module upon a 0
to 1 transition. Upon completion of the latch process the external latch valid
bit LATEXT_VAL will be set to 1.
Maintaining a Reference Point:
The storage of a present counter value may also accomplished via the Index
pulse from the encoder. First the index latch enable bit must be set,
EN_LACT, to a value 1. The encoder present value will be latched upon the
low to high transition of the Index input. Upon completion of the data latch
process the Index Latch Valid bit, LACT_VAL will be set to 1.
Attention
For the process data configuration of these bus modules please refer to chapter
"Process data architecture for MODBUS/TCP" in the process image descripti-
on of the corresponding coupler/controller.
