Siemens MICROMASTER 420 Operating Instructions Manual page 72

Information for the CANopen master
The following values must be taken into account for the maximum cable length
between a MICROMASTER and a CANopen-Master with the same values:
CAN interface chip
Line driver
Line driver
Opto-coupler
Cable time lag
Signal propagation time = 0,85 . T
(The value 0.85 is permanently set in the MICROMASTER)
This produces the following equation:
0,85
⋅
2 Baudrate
0,85
⋅
2 Baudrate
The following approximate cable lengths are obtained from this formula:
Table 4-3
Baud rate (kbit/s)
72
= T = In+out 26 ns
CAN
= T
Transceiver
= T
Transceiver
= T
Optocouler
= T = 5 ns/m
Ltg
+ +
- ([T In out] [T
CAN Transceive
T
Ltg
+ +
- ([26 ns] [80 ns 150 ns]
ns
5
m
Maximum cable lengths between two bus nodes with the delay times of
MICROMASTER 420/430/440
Maximum network range (m)
1000
800
500
250
125
50
20
10
(Tx) = 80 ns
(Rx) = 150 ns
= 40 ns
, 0 85
=
Bit
Baudrate
+ + ⋅
Tx Rx] [2 T
r Optocouple
+ ⋅
[2 40 ns])
18
39
103
273
613
1633
4183
8433
CANopen Option Module
Issue 01/05
])
r
=
Operating Instructions
6SE6400-5BC00-0BP0