2.8.4 External Start/Stop - Siemens SIMATIC S5 Manual

The maximum braking distance can be calculated for tv = 3 ~ as follows:
Where:
: start-stop frequency
maximum frequency
:
F : theoretical maximum frequency = (frnax - f~J/O.95
: acceleration time 10.,.3c]
: ramp-up constant = F/a
a : rate of frequency increase

2.8.4 External Start/Stop

The digital input "external start/stop" has two functions. A signal change from "O" to"1" serves
as an "external stop", the change from "1" to "O" serves as an "external start enable".
External stop
During the processing of a traversing job, a signal change from "O" to"1" at this digital input
causes the error message "external stop received", the traversing job and current mode are ter-
minated. If the external stop is received while processing a machining program (automatic
mode), the machining program is interrupted.
External start
If a"1" is set at this digital input before the start of a traversing job, the traversing job is inter-
preted by the IP247 but is not executed. If the job is permissible, you will obtain the message
"motor waiting for external start". The negative edge of the signal at the digital input causes the
traversing job to be executed.
Only one single job can be waiting for execution. Other jobs during the waiting time are not al-
lowed. If a further operating instruction is sent to the IP247, the job currently waiting for execu-
tion is deleted, A stop command in conjunction with any mode causes error-free termination.
The message "motor waiting for external start" is reset. Any command other than "stop" leads to
the error message "job not permitted".
The external start enable is also effective in the automatic mode with traversing jobs and dwell
times. If the signal "1" is set at this digital input before the start of the automatic mode (mode 8),
the machining program starts with the start command and is executed up to the first traversing
job or the first dwell time. The dwell time or traversing job then causes the message "motor wait-
ing for external start". The negative edge at the digital input enables the traversing movement or
dwell time. A further statement within the started machining program cannot be blocked with the
"external start enable", since the positive edge of the signal at the digital input is then evaluated
as "external stop". (Exception: module waiting for "enter signal" after "programmed halt" (M OO).)
If a"1" is set at this digital input before the start of the "automatic single statement" mode (mode
9), the start command also leads to the execution of the machining program up to the first pro-
grammed traversing job or first dwell time. The "enter command" then causes the message
"motor waiting for external start". The first traversing job or the first dwell time and all the offsets
and switchovers programmed after it are then executed on the negative edge of the signal at the
digital input, If signal "1" is set again at the digital input during the execution of the traversing job
+ -c ~ (e (+tv/T) . 1)) + fe,s
v
x b)
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