Epson RC620 Manual page 177

(2) Separate each slave from the network
4.1.3.5 Network Configuration and Specifications
(1) Maximum Network Length and Drop Line Length
(2) Terminating Resistor
(3) Cable and Branch Tap
(4) Communications Power Supply
RC620 Option Fieldbus I/O Rev.8
Check for each slave. The trouble point is where error condition changes into normal
condition.
Master PLC
Branch Tap
Communications
Power Supply
Terminating
Resistor
Check that the cables used on the network meet the following specifications.
Type Baud Rate
Thick Cable 500 kbps
250 kbps
125 kbps
Thin Cable 500 kbps
250 kbps
125 kbps
Ensure that two terminating resistors are connected to both ends of the network (trunk
line). The terminating resistor should be 121 Ω 1/4 W.
The cables and branch taps should meet the DeviceNet specifications.
The communications power supply should be dedicated to DeviceNet.
Do not share the communications power supply with I/O devices. *
* Noise due to load on/off may affect DeviceNet communications via the
communications power supply.
(The noise causes remote I/O communication error, Busoff detection, and broken
unit.)
Branch Tap
Slave
Slave
Second
Max. Network
Length
100 m
250 m
500 m
100 m
100 m
100 m
4. Troubleshooting (DeviceNet)
Slave Slave
First
Separate slaves one by one from
the network.
Drop Line Total Drop
Length Line Length
39 m
78 m
156 m
6 m
39 m
78 m
156 m
Terminating
Resistor
167