Product overview
EL37x2
26
Version: 3.5
• Universal zero point
1.1.2000 00:00
, i.e. for variable evaluations an offset of 2000 years has to be
added
• Scope up to
64 bit
(sufficient for 584 years). However, some EtherCAT slaves only support a 32 bit
scope, i.e. the register overflows locally after approx. 4.2 seconds and starts again at 0.
The following 3 data types are recommended for handling DC times
•
T_DCTIME
from TcEtherCAT.lib
This is based on T_ULARGE_INTEGER and is therefore unsigned. It can be used for linking with
suitable hardware variables
•
T_ULARGE_INTEGER
from TcUtilities.lib
Unsigned 64-bit data type
•
T_LARGE_INTEGER
from TcUtilities.lib
Signed 64-bit data type, negative numbers are represented in two's complement notation (underflow
below 0 --> 0xFFFF FFFF FFFF FFFF etc.)
TcUtilities.lib (section INT64) provides numerous relevant functions. Of particular significance are the
cast functions LARGE_TO_ULARGE and vice versa.
This type should be used when working with time differences that may be negative.
If TwinCAT is used for external synchronization, negative times will inevitably occur in the offset values.
Note
64- vs. 32-bit representation
Some EtherCAT slaves can only handle 32 bit values for representing the DC time or han-
dle it as a process data. In order to prevent problems caused by overflow (every 4.2 sec-
onds), we strongly recommend using 64-bit times in the controller.
• 32-bit times supplied to the PLC must be complemented with the current High part
• In this case only the Low part (lower 32 bit) should be transferred to the hardware
This sample project
(https://infosys.beckhoff.com/content/1033/el37x2/Resources/zip/2469155979.zip) contains a function
block that cyclically adds the high part to a 32-bit DC time to make 64 bits.
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...
