Yokogawa EJA115 - Manual (Page 25)

IM 01C22T02-01E 5-3
5. CONFIGURATION
A maximum of 100 ms is taken for execution of AI
block. For scheduling of communications for combina-
tion with the next function block, the execution is so
arranged as to start after a lapse of longer than 100 ms.
In no case should two AI function blocks of the EJA
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.EPS
LIC100
FIC100
FC100
FI100
EJA
#2
LI100
EJA
#1
Figure 5.2 Example of Loop Connecting Function Block of
Two EJA 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.EPS
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 interval 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”
5.4 Setting of Tags and
Addresses
This section describes the steps in the procedure to set
PD Tags and node addresses in the EJA. There are
three states of Fieldbus devices as shown in Figure 5.4,
and if the state is other than the lowest
SM_OPERATIONAL state, no function block is
executed. EJA must be transferred to this state when an
EJA tag or address is changed.
UNINITIALIZED
(No tag nor address is set)
Tag clear Tag setting
INITIALIZED
(Only tag is set)
SM_OPERATIONAL
(Tag and address are retained, and
the function block can be executed.)
Address clear
F0504.EPS
Address setting
Figure 5.4 Status Transition by Setting PD Tag and Node
Address
EJA has a PD Tag (PT1001) and node address (245, or
hexadecimal F5) that are set upon shipment from the
factory unless otherwise specified. To change only the
node address, clear the address once and then set a new
node address. To set the PD Tag, first clear the node
address and clear the PD Tag, then set the PD Tag and
node address again.
Devices whose node address have been cleared will
have the default address (randomly chosen from a
range of 248 to 251, or from hexadecimal F8 to FB).
At the same time, it is necessary to specify the device
ID in order to correctly specify the device. The device
ID of the EJA is 5945430003xxxxxxxx. (The
xxxxxxxx at the end of the above device ID is a total
of 8 alphanumeric characters.)