BECKHOFF ET1100 - Manual (Page 66)

PDI description
III-52 Slave Controller – ET1100 Hardware Description
6.2.6 Output Enable/Output Configuration
The ET1100 has an Output Enable signal OE_EXT and an Output Configuration signal OE_CONF.
With the OE_EXT signal, the I/O signals can be cleared/put into a high impedance state. OE_CONF
controls the output driver’s behavior after the output enable signal OE_EXT is set to low or the
SyncManager Watchdog is expired (and not disabled).
Table 55: Output Enable/Output Configuration combinations
OE_CONF
OE_EXT
0 1
0
I/O driver: ON
I/O: 0
I/O driver: ON
I/O: 0 if WD is expired, else
output data
1
I/O driver: OFF I/O driver: OFF if WD is expired or
output event has not occurred
since WD was last activated
I/O: 0 if WD is expired, else
output data
OE_CONF is ignored in bidirectional mode, I/O will be driven low during output events if OE_EXT is 0
or the watchdog is expired.
NOTE: I/O drivers are off until the EEPROM is loaded regardless of OE_CONF, OE_EXT, and watchdog.
6.2.7 SyncManager Watchdog
The SyncManager watchdog (registers 0x0440:0x0441) must be either active (triggered) or disabled
for output values to appear on the I/O signals. The SyncManager Watchdog is triggered by an
EtherCAT write access to the output data registers.
If the output data bytes are written independently, a SyncManager with a length of 1 byte is used for
each byte of 0x0F00:0x0F03 containing output bits (SyncManager N configuration: buffered mode,
EtherCAT write/PDI read, and Watchdog Trigger enabled: 0x44 in register 0x0804+N*8). Alternatively,
if all output data bits are written together in one EtherCAT command, one SyncManager with a length
of 1 byte is sufficient (SyncManager N configuration: buffered mode, EtherCAT write/PDI read, and
Watchdog Trigger enabled: 0x44 in register 0x0804+N*8). The start address of the SyncManager
should be one of the 0x0F00:0x0F03 bytes containing output bits, e.g., the last byte containing output
bits.
The SyncManager Watchdog can also be disabled by writing 0 into registers 0x0440:0x0441.
The Watchdog Mode configuration bit is used to configure if the expiration of the SyncManager
Watchdog will have an immediate effect on the I/O signals (output reset immediately after watchdog
timeout) or if the effect is delayed until the next output event (output reset with next output event). The
latter case is especially relevant for Distributed Clock SYNC output events, because any output
change will occur at the configured SYNC event.
Immediate output reset after watchdog timeout is not available if OUTVALID mode set to watchdog
trigger (0x0150[1]=1).
For external watchdog implementations, the WD_TRIG (watchdog trigger) signal can be used. A
WD_TRIG pulse is generated if the SyncManager Watchdog is triggered. In this case, the internal
SyncManager Watchdog should be disabled, and the external watchdog may use OE_EXT and
OE_CONF to reset the I/O signals if the watchdog is expired. For devices without the WD_TRIG
signal, OUTVALID can be configured to reflect WD_TRIG.