Product overview
EL37x2
19
Version: 3.5
Note
Maximum sampling frequency
A smaller period than 10 µs is not permitted for the EL37x2. The maximum sampling fre-
quency for the EL37x2 is therefore 100 kSps (samples per second).
Regarding the calculation of SYNC0 from the SYNC1 pulse based on manual specification
of an oversampling factor, please note that for SYNC0 only integer values are calculated at
nanosecond intervals.
Sample: 187,500 µs is permitted, 333.3 is not.
Sample:
For SYNC1 = 1 ms oversampling factors such as 1,2,5 or 100 are permitted, but not 3! If implausible values
are use the terminal will reach the OP state but will not supply any process data. This may result in a working
counter error.
The 16-bit measured values accumulated in the buffer are sent as a packet to the higher-level control
system. For two channels and n = 100, 2 x 2 x 100 = 400 bytes of process data are transferred during each
EtherCAT cycle.
Time-related cooperation with other terminals
ADC data sampling in the EL37x2 is triggered by an interrupt that is generated by the local clock in the
terminal. All local clocks in the supporting EtherCAT slaves are synchronized. This enables EtherCAT slaves
(here: terminals) to sample measured values simultaneously (simultaneous interrupt generation),
independent of the distance between them
. This simultaneity is within the distributed clock precision range of
< 100 ns.
Sample:
Matching between two EL37x2:
The EtherCAT master, e.g. Beckhoff TwinCAT, configures both EL37x2 such that their SYNC1 signals occur
at the same time. Assumption: The EtherCAT bus cycle time is 500 µs. SYNC1 is therefore triggered every
500 µs in all EL37x2. If both terminals operate with a corresponding oversampling factor (e.g. 20), the
SYNC0 pulse correlating to SYNC1 will occur simultaneously in all EL37x2, in this example every 25 µs. One
application option would be "distributed" oscilloscope with a sampling frequency of 40 kSps, for example.
If the EL37x2 use different oversampling factors, their SYNC0 pulses no longer occur simultaneously. The
higher-level SYNC1 pulse is retained.
If a value is entered under "Shift time (µs)" in the TwinCAT System Manager (DC tab, Advanced Settings) for
the SYNC0 pulse in an EL37x2, the EL37x2 manipulated in this way will start output sooner or later,
according to the set value. This can be useful in cases where a wanted signal has to be sampled at a higher
frequency than the 100 kSps permitted for the EL37x2, and several interconnected EL37x2 are therefore
used.
Sample:
For sampling a wanted signal at 200 kSps two EL37x2 are used side-by-side and subjected to the same
wanted signal (e.g. channel 1 in both terminals). Assume a bus cycle of 1 ms, an oversampling factor in both
EL37x2 of n = 100, and therefore maximum speed at 10 µs interval or 100 kSps. In the second EL37x2 an
additional
Shift Time of 5 µs is entered manually for this terminal in the System Manager (DC tab, Advanced
Settings, SYNC0, User Defined). This means all SYNC0 pulses for this EL37x2 will occur 5 µs later than for
the first EL37x2.
Note
Synchronization and provision of process data
Since the SYNC1 pulse is derived from the SYNC0 pulse, each SYNC1 pulse of the sec-
ond EL37x2 will occur 5 µs after the SYNC1 pulse of the first EL37x2. Please note that this
may influence the timing of the process data allocation for the EtherCAT frame, since this is
controlled by the SYNC1 pulse.
Summary of Contents for EL3702
Page 2: ......
Page 6: ...Table of contents EL37x2 6 Version 3 5...
Page 83: ...Commissioning EL37x2 83 Version 3 5 Fig 92 Incorrect driver settings for the Ethernet port...
Page 142: ...Commissioning EL37x2 142 Version 3 5 Fig 184 Process data tab SM0 EL37x2...
Page 143: ...Commissioning EL37x2 143 Version 3 5 Fig 185 Process data tab SM1 EL37x2...
