Siemens SINUMERIK 840D sl Function Manual page 1160

Detailed description
2.12 Block descriptions
2.12.10 FB 29: Signal recorder and data trigger diagnostics
Signal recorder
The "diagnostics" FB allows various diagnostic routines to be performed on the PLC user
program. A diagnostic routine logs signal states and signal changes. In this diagnostic
routine, function number 1 is assigned to the "Func" parameter. Up to 8 signals of the
parameters "Signal_1" to "Signal_8" are recorded in a ring buffer each time one of the
signals changes. The current information of parameters "Var1" as BYTE value, and "Var2"
and "Var3" as INTEGER values are also stored in the ring buffer.
The number of past OB 1 cycles is also stored in the buffer as additional information. This
information enables the graphical evaluation of signals and values in OB 1 cycle grid. The
first time the "diagnostics" FB is called in a new PLC cycle, the "NewCycle" parameter must
be set to TRUE. If the "diagnostics" FB is called several times in the same OB 1 cycle, the
"NewCycle" parameter must be set to FALSE for the second and subsequent calls. This
prevents a new number of OB 1 cycles from being calculated.
The ring buffer, specified by the user, must have an ARRAY structure specified as in the
source code. The array can have any number of elements. A size of 250 elements is
recommended. The "ClearBuf" parameter is used to clear the ring buffer and set the BufAddr
pointer (I/O parameter) to the start. The instance DB related to the FB is a DB from the user
area and is to be transferred to the FB "Diagnostics" with the parameter "BufDB".
Data trigger
The data trigger function is intended to allow triggering on specific values (or bits) at any
permissible memory cell. The cell to be triggered is "rounded" with a bit mask ("AndMask"
parameter) before the "TestVal" parameter is compared in the diagnostic block.
Note
The source code for the function is available in the source container of the basic-program
library under the name Diagnose.awl.. The instance DB and the ring buffer DB are also
defined in this source block. The function call is also described in the function. The DB
numbers and the call must be modified.
176
Basic logic functions: PLC Basic program powerline (P3 pl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0