Delta RMC101 User Manual
Page 363
Ethernet 5.2
Communications
5-113
1 or more
0.14%
1.0%
3.0%
5.6%
8.9%
2 or more
0.028%
0.23%
0.80%
1.7%
3.0%
3 or more
0.0020%
0.023%
0.12%
0.35%
0.74%
4 or more
0.000025%
0.0013%
0.011%
0.052%
0.14%
5 or more
0.0%
0.000049%
0.00066%
0.0044%
0.017%
6 or more
0.0%
0.000001%
0.000041%
0.00029%
0.0020%
7 or more
0.0%
0.0%
0.000002%
0.000017%
0.00038%
8 or more
0.0%
0.0%
0.0%
0.0%
0.000069%
9 or more
0.0%
0.0%
0.0%
0.0%
0.000005%
The above statistics were captured on a network using a switch. Networks using a hub will
experience higher rates of collisions for the same utilization because the probability of a collision
increases with more devices.
Delays Incurred by Collisions
The time delayed for each frame depends on the baud rate (10 or 100 Mbps) and frame size. The
following chart shows the total minimum and maximum delays incurred by a frame having from
zero to sixteen collisions assuming the maximum frame size utilized by a RMC I/O frame. Notice
that only the 10 Mbps section of the chart applies to the switch-to-RMC segment of the LAN since
the RMC ENET is 10 Mbps.
10 Mbps Delays
100 Mbps Delays
Collisions
Min
(ms)
Max
(ms)
Min
(ms)
Max
(ms)
0
0.000
0.198*
0.000
0.020*
1
0.013
0.502
0.001
0.050
2
0.026
0.909
0.003
0.091
3
0.038
1.52
0.004
0.152
4
0.051
2.54
0.005
0.254
5
0.064
4.38
0.006
0.438
6
0.077
7.86
0.008
0.786
7
0.090
14.6
0.009
1.46
8
0.102
27.9
0.010
2.79
9
0.115
54.3
0.012
5.43
10
0.128
107.
0.013
10.7
11
0.141
160.
0.014
16.0
12
0.154
212.
0.015
21.2
13
0.166
265.
0.017
26.5
14
0.179
317.
0.018
31.7
15
0.192
370.
0.019
37.0
16
0.205
423.
0.020
42.3
* Even with no collisions, a frame may have to wait for the wire to be clear before being sent. This is
called deferral.
Example:
Suppose the Ethernet statistics for the RMC ENET show that the highest number of collisions for any
frame is six (6). How long of a delay is this? Given that the RMC ENET runs at 10 Mbps, the above
chart shows that a frame will six collisions would have been successfully delivered between 0.077 ms
and 7.86 ms from when it was intended to be sent.