MS/TP Bus cable recommendations - Metasys - LIT-12011034 - General System Information - Metasys System

The MS/TP bus supports much higher baud rates than the N2 bus. Higher baud rates make the MS/TP bus less fault tolerant and less immune to interference from inductive noise sources that may be present in the application environment.

For the best performance on MS/TP bus applications, use 22 AWG stranded wire in a shielded cable with proper cable shield grounding. This recommendation applies to both local and Remote Field Bus installations. Other wire gauges and non-shielded cable may provide acceptable bus performance in many applications, especially applications that have short cable runs and low ambient inductive noise levels.

Table 1 provides cable recommendations for MS/TP applications. The recommended FC bus and SA bus cables are available from Belden CDT Inc. and Anixter, Inc.

Alternative cables may be used in MS/TP applications. Table 2 provides information regarding the relationship between baud rate, wire gauge, wire length, and supported device numbers. You can also use the information provided in Table 2 to determine if existing cable runs may be used in a retrofit or upgrade MS/TP application.

Note: In Table 1, the shielded bus and cable types are recommended; the non-shielded bus and cable types are acceptable.

Table 1. Cable for FC Buses and SA Buses in order of preference
Bus and cable type	Non-plenum applications		Plenum applications
Bus and cable type	Part number	O.D.	Part number	O.D.
FC Bus: 22 AWG Stranded, 3-Wire Twisted Shielded Cable	Anixter: CBL-22/3-FC-PVC Belden®: B5501FE	0.138 in.	Anixter: CBL-22/3-FC-PLN Belden: B6501FE	0.140 in.
SA Bus (terminal block): 22 AWG Stranded, 4-Wire, 2 Twisted-Pair Shielded Cable	Anixter: CBL-22/2P-SA-PVC Belden: B5541FE	0.209 in.	Anixter: CBL-22/2P-SA-PLN Belden: B6541FE	0.206 in.
SA Bus (modular jack): 26 AWG Solid 6-Wire, 3 Twisted-Pair Cable	—	—	Anixter preassembled: CBL-NETWORK25 CBL-NETWORK50 CBL-NETWORK75 CBL-NETWORK100	0.15 in.
FC Bus: 22 AWG Stranded, 3-Wire Twisted Non-Shielded Cable	Belden: B5501UE	0.135 in.	Belden: B6501UE	0.131 in.
SA Bus (terminal block): 22 AWG Stranded, 4-Wire, 2 Twisted-Pair Non-Shielded Cable	Belden: B5541UE	0.206 in.	Belden: B6541UE	0.199 in.

Note: We strongly recommend 3-wire (for FC bus) and 4-wire, 2 twisted-pair (for SA bus), 22 AWG stranded, shielded cable. A 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. Observe the shield grounding requirements.

Note: We recommend 26 AWG solid, 6-wire (3 twisted pairs) cable as the best fit for fabricating modular cables with the modular jack housing assembly. Be sure the cable you use fits the modular jack housing. The preassembled cables that are available from Anixter (Part No. CBL-NETWORKxxx) use 24 gauge wire.

Table 2. FC Bus wire gauge and FC Bus baud rate
AWG wire gauge	Maximum cable length and device connections limit	Baud rate
		9600	19,200	38,400	76,800
18	Maximum cable length per Bus segment (m [ft])	1,524 (5,000) (APR)	1,524 (5,000) (APR)	1,219 (4,000) (NR)	609 (2,000) (NR)	305 (1,000) (NR)
	Maximum number of devices (per segment / per FC Bus)	25/25 (APR)	50/50 (APR)	50/100 (NR)	10/30 (NR)	50/100 (NR)
20	Maximum cable length per Bus segment (m [ft])	1,524 (5,000) (APR)	1,524 (5,000) (APR)	1,524 (5,000) (APR)	1,524 (5,000) (NR)	1,219 (4,000) (NR)
	Maximum number of devices (per segment / per FC Bus)	25/25 (APR)	50/50 (APR)	50/100 (APR)	40/100 (NR)	50/100 (NR)
22	Maximum cable length per Bus segment (m [ft])	1,524 (5,000) (A)	1,524 (5,000) (A)	1,524 (5,000) (Best)	1,524 (5,000) (A)
	Maximum number of devices (per segment / per FC Bus)	25/25 (A)	50/50 (A)	50/100 (Best)	50/100 (A)
24	Maximum cable length per Bus segment (m [ft])	1,524 (5,000) (APR)	1,524 (5,000) (APR)	1,524 (5,000) (APR)	1,524 (5,000) (APR)
	Maximum number of devices (per segment / per FC Bus)	25/25 (APR)	50/50 (APR)	50/100 (APR)	50/100 (APR)
26	Maximum cable length per Bus segment (m [ft])	1,524 (5,000) (APR)	1,524 (5,000) (APR)	1,524 (5,000) (APR)	1,524 (5,000) (APR)
	Maximum number of devices (per segment / per FC Bus)	25/25 (APR)	50/50 (APR)	50/100 (APR)	50/100 (APR)
A = Acceptable APR = Acceptable with Possible Restrictions NR = Not Recommended

Note: The maximum number of devices is reduced at lower baud rates (9,600, 19,200) due to increased token loop times.

Note: 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.

Note: The MS-NAE55xx-0 cannot communicate at 76,800 baud.

MS/TP Bus cable recommendations - Metasys - LIT-12011034 - General System Information - Metasys System - Release 11.0

MS/TP Communications Bus Technical Bulletin