Omron SYSMAC 3G8F7-CLK13-E Operation Manual page 152

Communications Cycle Time
Maximum Communications Cycle Time Delay with Node Addresses Set in Order
Calculation Example for
Optical Ring Networks
with H-PCF Cable
132
With a Controller Link Network, the token is moved for the following.
• Normal token passing
• Token passing for new node checks by the polling node (depends on the
number of polled nodes set in the network parameters)
• Token passing for responses to messages.
Although the actually delay time will depend on the location of the line discon-
nection point, differences in the time required to receive the token can be
reduced by setting node addresses in order on the network.
The maximum delay in the communications cycle time can be calculated as
follows if the node addresses are set in the order that the nodes are con-
nected in the network.
A: Number of polled nodes per communications cycle
(value specified in the network parameter)
B: Number of nodes that send messages during the communications cycle
C: Number of nodes connected to network
D: Extra communications time for long-distance cable connections.
If L is the cable length in km, then F = 7 × L μs for H-PCF cable and
F = 5 × L μs for GI cable.
(A × 4 + B × 2 + 1) × (3 × C + D) (μs)
Communications conditions are as follows:
Type:
Transmission medium:
Transmission distance:
Baud rate:
Network parameters:
Max node address:
Polled nodes per comm cycle:
Event-frames per comm cycle: 35
Network configuration:
Nodes that send messages:
Bytes in all messages sent:
In this example, B to F in the equation have the following values.
A: 4
B: 8
C: 2
D: 7 × 8
The communications cycle time delay for Token Ring Mode is thus as follows:
(4 × 4 +2 × 2 + 1) × (3 × 8 + 7 × 8) = 1,680 (μs)
≅ 1.7 (ms)
The percentage change for active data links would be as follows (refer to Cal-
culation Example for Optical Ring Networks with H-PCF Cable under 8-2-1
Active Data Links):
(111 + 1.7)/111 × 100
≅ 101.5 (%)
The percentage change for inactive data links would be as follows (refer to
Calculation Example for Optical Ring Networks with H-PCF Cable under 8-2-2
Inactive Data Links):
Optical Ring
H-PCF cable
8 km
2 Mbps (fixed)
Defaults
62
4
8 nodes
2 nodes
2,012 × 2 bytes
Section 8-2