Micromod Micro-DCI: 53MC5000 MicroLink - Manual (Page 10)

3.2 ASSESSING THE COMMUNICATIONS LOAD
Data through-put of the MicroLink network depends primarily on the communications data transfer
rate. Column 3 in Table 3-1 shows the number of Transactions per Second that the network can
support for each of the four available data rates.
The number of Transactions per Second required for a specific application can be calculated by de-
termining the number of transactions required at each node. The total of the transactions at each
node provides the total network load. If this load is greater than the maximum TPS for the selected
data rate, then the loading at individual nodes must be reduced or the data rate increased.
Procedural steps to assess the communications load are provided in sub-section 3.2.1 and an ex-
ample is provided in sub-section 3.2.2.
3.2.1 PROCEDURE TO ASSESS COMMUNICATIONS LOAD
To assess the network load, perform the following steps:
1. Calculate the loads for each 53SU5000 SUPERVISOR-PC unit by accessing the SU-
PERVISOR templates (IB 53SU5000, Section 4, Database) for the following information:
1a. Determine the total number of CON templates
with B02 set to a value other than 255.
1b. Determine the total number of F-TRAN instrument
reads or writes in a single scan by counting the
operands containing INS as module type.
1c. SUPERVISOR-PC unit loads = 1a + 1b.
1d. Reference the appropriate data transfer rate (Mbits/s) column in Table 3-2 to
determine the shortest scan time possible for the loads calculated in 1c. If this
scan time is still too long in duration for system requirements, then the loads must
be reduced by modifying the SUPERVISOR-PC unit CON templates configuration
or the F-TRAN instrument reads and writes.
Repeat this process for each SUPERVISOR-PC unit in the network.
2. Convert the SUPERVISOR-PC unit loads to SUPERVISOR-PC unit TPS with TPS =
loads/Scan File Index (SUP0.B03). Sum the TPS for each SUPERVISOR-PC unit. Refer-
ence the appropriate data transfer rate (Mbits/s) column in Table 3-1 to ensure the corre-
sponding network TPS is not exceeded.
3. Allow 50 TPS for each PC unit with the 53WS5000 product package installed. Total
TPS = Number of PC units with the 53WS5000 product package installed X 50.
Section 3. MicroLink Network Sizing
8