Specifications

Table 12: FC Bus Wire Gauge and FC Bus Baud Rate
1,524 (5,000)
(A)
1,524 (5,000)
(Best)
1,524 (5,000)
(A)
1,524 (5,000)
(A)
Maximum Cable Length per
Bus Segment (m [ft])
22
50/100
(A)
50/100
(Best)
50/50
(A)
25/25
(A)
Maximum Number of Nodes
(per Segment / per FC Bus)
1,524 (5,000)
(APR)
1,524 (5,000)
(APR)
1,524 (5,000)
(APR)
1,524 (5,000)
(APR)
Maximum Cable Length per
Bus Segment (m [ft])
24
50/100
(APR)
50/100
(APR)
50/50
(APR)
25/25
(APR)
Maximum Number of Nodes
(per Segment / per FC Bus)
1,524 (5,000)
(APR)
1,524 (5,000)
(APR)
1,524 (5,000)
(APR)
1,524 (5,000)
(APR)
Maximum Cable Length per
Bus Segment (m [ft])
26
50/100
(APR)
50/100
(APR)
50/50
(APR)
25/25
(APR)
Maximum Number of Nodes
(per Segment / per FC Bus)
A = Acceptable
APR = Acceptable with Possible Restrictions
NR = Not Recommended
1 The maximum number of devices is reduced at lower baud rates due to increased token loop times.
2 3-wire conductor (FC Bus), 22 AWG stranded, shielded cable is recommended. 22 gauge cable offers the best performance
for various baud rates, cable distances, and number of trunk devices primarily due to lower conductor-to-conductor capacitance.
Shielded cable offers better overall electrical noise immunity than non-shielded cable.
3 The MS-NAE55xx-0 cannot communicate at 76,800 baud.
Screw Terminal Blocks for Connecting the Bus Cable
Both the FC bus and SA bus terminations have pluggable screw terminal blocks that allow you to connect the bus
devices in a daisy-chain configuration. Connect the devices to the FC bus segments and SA bus as shown in Figure
14.
Note: The SHLD terminal on the FC bus terminal block is electrically isolated from ground and is provided as a
convenient terminal for connecting the cable shield in a daisy-chain on the bus segment.
Note: Do not mix RJ-style modular (phone) jack and screw terminal devices on the SA bus. Due to the permanent
internal SA bus EOL termination contained in FECs, FACs, IOMs, and VMAs, using both the phone jack and
terminal block effectively puts the EOL termination in the middle of the SA trunk, creating a star network
configuration. This configuration violates the RS-485 network wiring guidelines and can cause unpredictable
communication problems.
36MS/TP Communications Bus Technical Bulletin