Horner APG RCS SmartStix - Manual (Page 29)

CH.2 15 MAR 2003 PAGE 29
MAN0305-04
6. For a section of cable between two nodes, the cable shield is connected to the cable shield input at
one end of the cable only.
7. A CAN network (without repeaters) is limited to 64 nodes (with 63 cable segments) with a maximum
combined cable length of 1500 ft. at 125KBaud.
8. Up to four CAN network segments, which adhere to the above rules, may be connected together
using three CAN repeaters. In this manner, a CAN network may be extended to 253 nodes with a
total cable distance of 6000 ft. at 125KBaud.
b.
CsCAN or DeviceNet Cable
The 5-wire, multi-conductor copper cable used in CsCAN or DeviceNet network include:
1. Two wires used as a transmission line for network communications.
2. Two wires used to transmit network power.
3. One conductor used as an electromagnetic shield.
Cabling is available in a variety of current -carrying capacities. On a CsCAN or DeviceNet fieldbus, every
device must, at least, power its network transceivers from the network power supply. Some devices draw
all of their power from the network supply.
In CsCAN or DeviceNet, thick and thin cable is used as indicated:
1. Thick cable: Use for long distances and more power. Usually used for Trunk cable.
2. Thin cable: Use for shorter distances. Usually used for drop cables or where cable flexibility is
needed.
Table 2.4 - CsCAN / DeviceNet Cable Specifications
Thick Cable –
general specifications
(e.g., Belden 3082A) Two twisted shielded pairs –Common axis with drain wire in center.
One signal pair (#18), blue/white; One power power pair (#15) black/red.
Separate aluminized mylar shields around power pair and signal pair.
Overall foil/braid shield with drain wire (#18), bare * . High Speed (Vp=75% min),
low loss, low distortion, data pair (to keep propagation delays to a minimum).
8 amp maximum current capacity. PVC insulation on power pair. Industrial
temperature range. High flexibility.
Thin Cable –
general specifications
(e.g., Belden 3084A) Two twisted shielded pairs –Common axis with drain wire in center.
One signal pair (#24), blue/white; One power power pair (#22) black/red.
Separate aluminized mylar shields around power pair and signal pair.
Overall foil/braid shield with drain wire (#22), bare * . High Speed (Vp=75% min),
low loss, low distortion, data pair (to keep propagation delays to a minimum).
3 amp maximum current capacity. PVC insulation on power pair. Industrial
temperature range. High flexibility
Network Topology Bus with limited branching (truckline / dropline)
Redundancy Not Supported
Network Power for Node
devices Nominal 24 VDC
±
4%
Allowed Nodes (Bridging
excluded) 64 nodes
Data Packet Size 0-8 bytes with allowance for message fragmentation
Duplicate Address Detection Addresses verified at power-up
Error Detection / Correction CRC – retransmission of message if validity not acknowledged by
recipient.
*
The drain wire connects shields within the cable and serves as a means to terminate the shield into the
connector.