User`s guide

Page 95

Controlinc 1746-C (Version 5.21) Network Master Users Guide (2004-11-18)

Below is a table of empirical values demonstrating the difference in network performance when

changing the number of additional valves to scan in the scan time slice.

This network scan scenario is for base readings with

• No Network Writes – Only Polling

• Zero M0/M1 transfer delays waiting for the RLL to interface with the 1746-C.

• 60 … Number of nodes configured to be on network

• 25 … Scan Period

• Polling base scan data … no additional registers.

• No additional delay time for Modbus response messages from the actuators.

Average Network Scan Time (seconds) after changing the

number of

“Additional Valves to Scan in the Network Scan Time Slice”

# Nodes “Talking”

… On-Line

0 1 2 3 5 7 9

1 of 60 (#60) 0.2 0.2 0.2 0.2 0.2 0.2 0.2

2 of 60 (#59 – 60) 0.3 0.3 0.3 0.3 0.3 0.3 0.3

3 of 60 (#58 – 60) 0.4 0.4 0.4 0.4 0.4 0.4 0.4

6 of 60 (#55 – 60) 0.7 0.6 0.6 0.6 0.6 0.6 0.6

12 of 60 (#49 – 60) 1.3 1.2 1.1 1.1 1.0 1.0 1.0

24 of 60 (#37 – 60) 2.6 2.4 2.2 2.1 2.0 2.0 2.0

30 of 60 (#31 – 60) 3.2 3.0 2.7 2.7 2.6 2.5 2.5

36 of 60 (#25 – 60) 3.8 3.5 3.2 3.1 3.0 2.9 2.9

42 of 60 (#19 – 60) 4.4 4.1 3.8 3.7 3.6 3.5 3.4

48 of 60 (#13 – 60) 5.1 4.7 4.4 4.2 4.4 3.9 3.9

54 of 60 (#7 – 60) 5.7 5.3 4.9 4.7 4.5 4.4 4.3

60 of 60 (#1 – 60) 6.3 5.6 5.4 5.2 4.9 4.8 4.8

Note: For the most accurate scan period timing, do not use the 1

scan period after a power cycle (or

environment change) … wait until the 2

scan period or beyond.

The values in this table

“rounded values” and

have a precision of

(+/-) 0.2 seconds.

Because of this, these

numbers are only

appropriate for estimates

and trend analysis.