Process data and configuration

Oversampling settings, distributed clocks (DC)

The oversampling factor can be set on the "DC" tab (see figure below). The oversampling factor n is set to 1 in the delivery condition. When an entry is selected in the dialog, the correct sampling ratio at distributed clock level and the correct number of process data to be transferred are set automatically.

Sampling frequency If an oversampling factor is required that does not appear in the list, the user has to specify the ratio between the SYNC0 pulse and the SYNC1 pulse within the permitted limits, based on the information found in "Principles of the oversampling function". Please refer to the note “Maximum sampling frequency / minimum cycle time”.

The following sampling times / sampling frequencies apply to EL5101-0011:

"StartTimeNextLatch"

The process data "StartTimeNextLatch" (index 1A01) is activated by default.
The “StartTimeNextlatch” process data is 32 bits wide. During each process data cycle the time is specified at which the next SYNC1 pulse and therefore the next block of sample values begins. “StartTimeNextLatch” thus changes in each cycle by the amount of that task cycle time with which this terminal is operated. This time specification is based on the terminal’s local Distributed Clocks time. The EL5101-0011 maps only the 64-bit distributed clocks time.
In this way all samples can be synchronized with other time data within the EtherCAT bus based on the known oversampling factor.

Sample:

The EL5101-0011 supplies in the regarded cycle with
cycle time = 1 ms (= 1,000,000 ns) and
oversampling factor n =  20,
a “StartTimeNextLatch” of 503,330,625,067,077,000_dec and 20 measured values (counter value) of 32 bits each as process data.

The time of measurement of the 5^th supplied position value is now to be determined, i.e. the Distributed Clocks time at which the 5^th position value was determined.
The currently delivered set of 20 counter values was started at the time:

503,330,625,067,077,000 – 1,000,000 (cycle time) = 503,330,625,066,077,000 ns.
The time interval between the samples is 1.000.000/20 = 50.000 ns.
The 5^th position value was thus determined at the time:
503,330,625,066,077,000 + ((5 - 1) * 50,000) = 503,330,625,066,027,000 ns

Special oversampling factor and Shift Time for the SYNC0 pulse

Setting the counter value - referencing:

Since incremental encoders do not deliver an unambiguous position value after switching on, a homing must be carried out.
The EL5101-0011 offers the option to set the reference point manually via "Set counter" (index 0x7000:03).

“Set counter” (index 0x7000:03)

• The value to be set as reference value (default: 0) is written in “Set counter value” (index 0x7000:11).
• The function is activated by setting the bit in “Set counter” (index 0x7000:03) to TRUE.
• The value from “Set counter value” (index 0x7000:11) is written in “counter value” (index 0x6000:11).
• The value of the bit in “Set counter done” (index 0x6000:03) is set to TRUE.
• After re-activation of "Set counter" (Index 0x7000:03), the next reference value can be written in "counter value" (Index 0x6000:11) only if the value of the "Set counter done" bit (index 0x6000:03) is FALSE.

Open circuit detection

• A separate open circuit detection can be activated for each of the channels A, B and C (index 0x8000:0B, 0x8000:0C, 0x8000:0D).
• The open circuit detection for channels A and B is activated by default.
• A differential voltage of -0.475 V > Vid >+0.475 V (typical, subject to change) is detected as an open circuit.
• If an open circuit is detected, it is indicated as process data "Open circuit” = TRUE. The bit in object 0x6000:07 is set. An open circuit is indicated separately in indices 0xA000:01 (track A), 0xA000:02 (track B) and 0xA000:03 (track C).
• “TxPDO state” also becomes TRUE if an open circuit is detected, since invalid data have to be assumed.

Further cyclic information

Furthermore, the EL5101-0011 offers the following cyclic information: