Yokogawa EJX930A - Manual (Page 32)

<5. Configuration>
5-3
IM 01C25T02-01E
5.3 Definition of Combining
Function Blocks
The input/output parameters for function blocks are
combined. As required, they can be combined with
the input of the control block. The setting is written
to the transmitter link object. See “Block setting” in
Section 5.6 for the details. It is also possible to read
values from the host at proper intervals instead of
connecting the transmitter block output to other
blocks.
The combined blocks need to be executed
synchronously with other blocks on the
communications schedule. In this case, change the
DPharp schedule according to the following table.
The values in the table are factory-settings.
Table 5.3 Execution Schedule of the DPharp
Function Blocks
Index Parameters
Setting (Enclosed is
factory-setting)
269
(SM)
MACROCYCLE_
DURATION
Cycle
(MACROCYCLE)
period of control or
measurement. Unit
is 1/32 ms. (16000 =
0.5 s)
276
(SM)
FB_START_ENTRY.1 AI1 block startup time.
Elapsed time from the
start of MACROCYCLE
specified in 1/32 ms.
(0 = 0 s)
277
to
291
(SM)
FB_START_ENTRY.2
to
FB_START_ENTRY.16
Not used.
A maximum of 30 ms is taken for execution of
AI block. For scheduling of communications for
combination with the next function block, the
execution is so arranged as to start after a lapse
of longer than 30 ms. In no case should function
blocks of the transmitter be executed at the same
time (execution time is overlapped).
Figure 5.3 shows an example of schedule based on
the loop shown in Figure 5.2.
F0502.ai
LIC100
FIC100
FC100
FI100
EJX
#2
LI100
EJX
#1
Figure 5.2 Example of Loop Connecting
Function Block of Two EJX with Other
Instruments
LI100
LIC100
FIC100 FC100
FI100
Commu-
nication
Schedule
OUT
IN
OUT
CAS_IN
BKCAL_OUT
BKCAL_IN
BKCAL_IN
BKCAL_OUT
IN
Unscheduled
Communication
Scheduled
Communication
F0503.ai
Macrocycle (Control Period)
Figure 5.3 Function Block Schedule and
Communication Schedule
When the control period (macrocycle) is set to more
than 4 seconds, set the following intervals to be
more than 1% of the control period.
- Interval between “end of block execution” and
“start of sending CD from LAS”
- Interval between “end of block execution” and
“start of the next block execution”