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12-20-2002
Figure Sheet 1-851-A
Page 10
In the example diagram (Figure 2-1), there is real-time data on D1 and 16 multiplexed data words on
D5. D1 contains the Edge Left Sensor value from a CDP-01. D5 is used to send 16 different values
from the CDP-01. For the real-time value, the CDP-01 sends the Edge Left Sensor value in D1 every
cycle. For the multiplexed time slice, the CDP-01 sends the Edge Right Sensor value in D5 during
time T0. During time T1, D5 contains the Line Edge Sensor value.
As you can see in the example on the previous page, 17 values are being sent over FifeNet, but only
two time slices of network bandwidth are used. The 16 values in time slice 5 are updated at a slower
rate than the value in time slice 1. The application dictates which method should be implemented.
FifeNet Master
The FifeNet protocol uses the time slice architecture described previously for configurable network
traffic. Without some synchronization, however, neither the SBPC-21-PB, nor the CDP-01, would
know where the time slice boundaries were located. This would create problems when they are trying
to send and receive data. This is one of the primary functions of the FifeNet Master, in this case, that
would be the SBPC-21-PB.
SBPC-21-PB Data Flow
In order to effectively connect two dissimilar networks, some means must be provided to collect the
data from each network and exchange it in a controlled manner so that no partial or incomplete data is
sent on either network. This is accomplished by using a block of memory in the SBPC-21-PB to
reassemble FifeNet time slice data and then, when it is complete, transfer it to the Profibus buffers for
transmission on Profibus. Keep in mind that the gateway has to be bidirectional so this process works
the same way for data traveling from Profibus to FifeNet. The diagram below shows the process:
Figure 2-2: SBPC-21-PB Data Flow Block Diagram
The time slice
buffers hold
the raw time
slice data.
This matrix is used to
connect Profibus
data to any memory
buffer location.
The memory array
is used to assemble
and hold data
passing through the
gateway.
This matrix is used
to connect any time
slice to any memory
buffer location.
Profibus data is
placed here for
transmission. FifeNet
transmit data is read
from here and sent to
FifeNet.
M
A
T
R
I
X
M
A
T
R
I
X
Profibus
Data
FifeNet
D1
D2
D3
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