Yokogawa EJX930A - Manual (Page 31)

<5. Configuration>
5-2
IM 01C25T02-01E
5.2 Network Definition
Before connection of devices with Fieldbus, define
the Fieldbus network. Allocate PD Tag and node
addresses to all devices (excluding such passive
devices as terminators).
The PD Tag is the same as the conventional
one used for the device. Up to 32 alphanumeric
characters may be used for definition. Use a
hyphen as a delimiter as required.
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 transmitter in the range of
the BASIC device. When the transmitter is used as
Link Master, place the transmitter 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 DPharp specification values.
Table 5.2 Operation Parameter Values of the
DPharp 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 the
transmitter, set a value of
4 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 the
transmitter, 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 the
transmitter, the setting
must be a value of 12 or
greater.