Horner APG RCS SmartStix User Manual
Page 30
PAGE 30
15 MAR 2003
CH.2
MAN0305-04
c.
Bus Length
Several factors affect the maximum length of the bus including the accumulated length of drop lines,
cable type, transfer rate and the number of drop lines. Although a branch is limited to one network per
drop, it can have multiple ports. A branch can not exceed 6 meters.
Table 2.5 - CAN Network Baudrate vs. Total Cable Length
Note: The following values apply to both CsCAN or DeviceNetworks except as indicated.
Thick Cable: Network Data Rate
Maximum Total Cable Length
1Mbit / sec. (Does not apply to DeviceNet.)
40m (131 feet)
500Kbit / sec.
100m (328 feet)
250Kbit / sec.
200m (656 feet)
125Kbit / sec.
500m (1,640 feet)
Thin Cable Maximum Total Cable Length
Maximum bus length is independent of network data rate. Maximum bus length is 100m.
Note: Network baud rates above 250Kbit/sec are not recommended for the MiniOCS /
MiniRCS . The potential for a high rate of network messages can cause an unacceptable
increase in the ladder scan rate.
d.
Bus Power and Grounding
When using CsCAN or DeviceNet:
1. A power supply of 24VDC (
±
4%) at 16A maximum is required for use in a CsCAN / DeviceNet network
2. With thick cable, a single network segment can have a maximum of 8A. To do this, the power supply
needs to be located in the center of two network segments.
3. Thin cable has maximum of 3A.
4. To ground the cable shield, connect to pin 3 as shown in Figure 2.16.
5. If local codes require the local CAN power supply to be earth grounded, connect the V- power
conductor to a good earth ground at one place only on the network, preferably at a physical endpoint.
If multiple power supplies are used, only one power supply must have V- connected to earth ground.
The remaining power supplies need to be isolated.
2.3.4
RS-232 Programming Port and Wiring
Table 2.6 – RS-232 Port Pins
Pin
Signal
Description
Direction
1
DCD
Always high
Out
2
RXD
Received Data
Out
3
TXD
Transmitted Data
In
4
DTR
Data Terminal Ready
In
5
GND
Ground
-
6
DSR
Data Set Ready
Out
7
RTS
Request to Send
In
8
CTS
Clear to Send
Out
9
RI
Ring Indicate
Out
Figure 2.17 – RS-232 Port
Pin 9
Pin 1