Installation guide

102 Estimating Network Performance
890 USE 100 00
3.21 Guidelines for a Single Network
3.21.1 Using MSTR Functions
Each controller on the network should have a maximum of four MSTR
functions active at the same time. Plan to have an MSTR function
transferring large quantities of registers (up to 100 maximum per
MSTR), rather than multiple MSTRs transferring small amounts of
registers. You can easily use Block instructions in your ladder logic
program to produce the block of contiguous registers required for each
MSTR.
Here are two timing examples. Each example is taken from a network
with 16 nodes, without global data being passed.
V Example 1: Every node has four MSTR functions active at all
times. Each MSTR is writing 50 registers. The average token
rotation time is 193 ms.
V Example 2: Every node has two MSTR function active at all times.
Each MSTR is writing 100 registers. The average token rotation
time is 126 ms.
Note that the same total quantity of data is being moved in the two
examples. By using fewer MSTRs to move the data, the second
example gives a 67 ms (about 35%) improvement in the average token
rotation time.