Operation Modes; Fig. 19 Worst-Case Reaction Time - Beckhoff EP1908 Operating Instructions Manual

Operation
Fig. 19: Worst-case reaction time
This assumes that a signal change occurs at the sensor and is transmitted to the input. A communication
error occurs at precisely the moment when the signal is to be transferred to the communication interface.
This is detected by the logic following the watchdog time of the communication link. This information should
then be transferred to the output, but a further communication error occurs here. This error is detected at the
output following the expiry of the watchdog time and leads to the switch-off.
This results in the following equation for the worst-case reaction:
ReactionTime = WD +
max Comm
with, for example
ReactionTime = 15 ms + 15
max
5.3

Operation modes

Operation mode Description
Single logic channel x/y Each channel is evaluated individually
Asynchronous analysis Mode for connecting devices with OSSD signals. The test pulses of the OSSD devices must not occur
OSSD, sensortest simultaneously. The maximum supported test pulse length is 350 µs.
deactivated In this mode the sensor test must be switched off for the input pair used.
Any pulse repetition OSSD, Mode for connecting devices with OSSD signals. The test pulses of the OSSD devices may occur
sensortest deactivated simultaneously. The maximum supported test pulse length is 350 µs.
In this mode the sensor test must be switched off for the input pair used.
Short cut channel x/y is no Mode for connecting safety mats. In this mode the two inputs of the input pair used are monitored for
module fault cross-circuit. If a cross-circuit occurs a person has walked on the safety mat, and the inputs report logical
0 in pairs.
The sensor test must be switched on for the inputs used.
Velocity control channel x / Speed monitoring channel x / individual evaluation channel y
Single logic channel y The first channel (x) returns a logical 1 if the current frequency is below the frequency set under Velocity
limit channel x.
The second channel (y) supplies the current signal state at input y.
The minimum supported frequency is 2 Hz. Values below this are shown as 0. The maximum supported
frequency is 500 Hz. Values above this result in a diagnostic messages of the EP1908-0002. This
message can be reset through a rising edge of the safe output signal ErrAck of the EP1908-0002.
Single logic channel x / Individual evaluation channel x / Speed monitoring channel y
Velocity control channel y The first channel (x) reports the current signal state of input x.
The second channel (x) returns a logical 1 if the current frequency is below the frequency set under
Velocity limit channel y.
The minimum supported frequency is 2 Hz. Values below this are shown as 0. The maximum supported
frequency is 500 Hz. Values above this result in a diagnostic messages of the EP1908-0002. This
message can be reset through a rising edge of the safe output signal ErrAck of the EP1908-0002.
Velocity control channel x/y Speed monitoring channel x / speed monitoring channel y
The first channel (x) returns a logical 1 if the current frequency is below the frequency set under Velocity
limit channel x.
The second channel (x) returns a logical 1 if the current frequency is below the frequency set under
Velocity limit channel y.
32
WD + RT
Comm Actuator
ms + 20 ms = 50 ms
Version: 3.0.0 EP1908