Yokogawa EJX930A - Manual (Page 29)

<5. Configuration>
5-2
IM 01C25R03-01E
The node address is used to specify devices for
communication purposes. Because this data is
too long for a PD Tag, the host uses the node
address in place of the PD Tag for communication.
A range of 20 to 247 (or hexadecimal 14 to F7) can
be set. The device (LM device) with bus control
function (Link Master function) is allocated from
a smaller address number (20) side, and other
devices (BASIC device) without bus control function
allocated from a larger address number (247) side
respectively. Place the EJX multivariable transmitter
in the range of the BASIC device. When the EJX
multivariable transmitter is used as Link Master,
place it in the range of the LM device. Set the range
of addresses to be used to the LM device. Set the
following parameters.
Table 5.1 Parameters for Setting Address Range
Symbol Parameters Description
V (FUN) First-Unpolled-
Node
Indicates the address
next to the address range
used for the host or other
LM device.
V (NUN) Number-of-
consecutive-
Unpolled-Node
Unused address range
The devices within the address range written
as “Unused” in Figure 5.1 cannot be used on a
Fieldbus. For other address ranges, the range is
periodically checked to identify when a new device
is mounted. Care must be taken to keep the unused
device range as narrow as possible so as to lessen
the load on the Fieldbus.
0xF7
0xF8
0xFB
0xFC
0xFF
V(FUN)
V(FUN)+V(NUN)
LM device
Unused V(NUN)
BASIC device
Default address
Portable device address
F0501.ai
Not used
0x00
0x0F
0x10
0x13
0x14
Bridge device
Figure 5.1 Available Range of Node Addresses
To ensure stable operation of Fieldbus, determine
the operation parameters and set them to the LM
devices. While the parameters in Table 5.2 are to
be set, the worst-case value of all the devices to
be connected to the same Fieldbus must be used.
Refer to the specification of each device for details.
Table 5.2 lists EJX specification values.
Table 5.2 Operation Parameter Values of the EJX
to be Set to LM Devices
Symbol Parameters
Description and
Settings
V (ST) Slot-Time Indicates the time
necessary for immediate
reply of the device. Unit of
time is in octets (256 μs).
Set maximum
specification for all
devices. For EJX, set a
value of 5 or greater.
V (MID) Minimum-Inter-
PDU-Delay
Minimum value of
communication data
intervals. Unit of time is in
octets (256 μs). Set the
maximum specification
for all devices. For EJX,
set a value of 4 or greater.
V (MRD) Maximum-
Reply-Delay
The worst case time
elapsed until a reply is
recorded. The unit is
Slottime; set the value
so that V (MRD) × V (ST)
is the maximum value
of the specification for
all devices. For EJX, the
setting must be a value of
12 or greater.
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 EJX 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 EJX 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
EJX schedule according to the following table. The
values in the table are factory-settings.