Omron CJ Series User Manual

A-11
Appendices
CJ-series PROFIBUS Master Unit Operation Manual for NJ-series CPU Unit (W509)
A-2 Bus Parameters
App
A
2
, B
2
, C
2
are constants (in s, determining the cycle time between the Unit and the CPU,
slave devices are the devices allocated to this Master Unit only, modules are the total number of I/O
modules, selected for the slave devices.
T
TR
=
 (Min. Slave Interval
Master
) [2]
The total Target Rotation Time is calculated as the sum of all individual Min. Slave Interval values for
each Master Unit on the PROFIBUS network.
From the total Target Rotation Time the Watchdog time for each slave device is calculated as fol-
lows:
T
WD
= 3 * T
TR
/ Baud rate [3]
in which: T
TR
is the total Target Rotation Time in
t
BIT
,
Baud rate is the selected baud rate value.
The Watchdog Time value is in turn used to calculate the total Data Control Time:
Data Control Time = 7 * T
WD
[4]
Based on measurements, the following values have been determined for the 6 factors in equation
[1]:
A2: 65.1 s, B2: 2 s, C2: 0.5 s
Baud rate
[kBits/s]
A1
[t
BIT
]
B1
[t
BIT
]
C1
[t
BIT
]
Minimum Min. Slave Interval
[t
BIT
]
[ms]
9.6 414 280 11 1250 130
19.2 418 280 11 1250 65.1
45.45 1942 361 11 1250 27.5
93.75 450 280 11 1250 13.3
187.5 1390 310 10 1250 6.67
500 2183 310 10 1850 3.7
1500 4339 310 11 4800 3.2
3000 11578 410 5 9600 3.2
6000 23556 800 10 19200 3.2
12000 47112 1600 20 38400 3.2

Omron CJ Series Specifications

General

Brand	Omron
Model	CJ Series
Category	Controller
Language	English