Filter
Top Products
42
9. Appendix
9. 4. Uni-Telway schematic
The Uni-Telway bus schematic was used by Telemecanique for older-generation drives and soft starters (ATV58, ATV28, ATS48, etc.)
marketed before the Modbus specifications were published on www.modbus.org.
Schematic diagram:
Type of trunk cable Cable with 2 twisted pairs shielded in pairs
Maximum length of bus 1000 m at 19200 bps
Maximum number of stations (without
repeater)
29 stations, i.e., 28 slaves
Maximum length of tap links
•20 m
• 40 m divided by the number of tap links on a multiple junction box
Bus polarization For the master and each slave:
• One 4.7 kΩ pull-up resistor to the 5 V
• One 4.7 kΩ pull-down resistor to the 0 VL
Line termination One 120 Ω 0.25 W resistor in series with a 1 nF 10 V capacitor
Common polarity Yes (0 VL) and high impedance placed between 0 VL and the ground in each station
1 nF
4.7 kΩ
4.7 kΩ
4.7 kΩ
4.7 kΩ
120 Ω
1 nF
120 Ω
5 V
0 V 0 V
4.7 kΩ
R
G
R
G
4.7 kΩ
5 V
5 V
0 V
R
G
D(B)
0VL
D(A)
Master
Slave 1
Slave n