M-system SC100 User Manual

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SC100/200 Series Users Manual EM-6337-B Rev.15
4.6. NESTBUS
SC200/210
The SC200/210 uses NestBus (RS-485) for peer-to-peer communication between other controllers and I/O modules. Soft-
ware terminal blocks of the NestBus devices are inter-connected to expand I/Os signals and share functions without needing
a master device.
Up to 16 NestBus devices are connected with twisted-pair cables in multi-drop conguration (cross wiring). An entire section
of cross-wired cables is called ‘segment.’
Each NestBus device is set with Card No. from 0 to F. For the SC200/210, set one in GROUP 00, ITEM 51. For remote I/O
modules, use the hardware DIP switch (blue rotary switch on the front). Be sure to assign each module with unique number.
4.6.1. NESTBUS CONNECTION
Use independently shielded twisted pair cables (CPEV-S φ0.9) to connect between NestBus devices. DO NOT use bound
cables, in order to eliminate unexpected interference from other signal lines.
An entire segment must be inside one building, with the maximum cable length of 1 kilometer.
Cross Wiring
• Cross wire between each device referring to the illus-
tration to the right.
• Be sure to connect (+) to (+) and (–) to (–).
• Connect shield terminal as designated for each de-
vice. For devices with no shield terminal, connect be-
tween the shields of each device.
• Earth the shield at single, independent ground point
within the system (grounding resistance 100 Ω or
less). The most appropriate point depends upon sys-
tems. There are also cases when leaving the shield
ungrounded gives a better result.
Terminating Resistor
• Connect a terminating resistor at both ends of the seg-
ment.
• Terminating resistor is incorporated in each device.
Close across T2 and T3 terminals to activate it. Con-
sult each device’s specications for exact terminal as-
signment of the resistor.
+
–
+
–
Jumper
T4
T1
T2
T3
To Other
NestBus
Devices
To Other
NestBus
Devices
Cross Wiring
+
–
T4
T1
T2
T3
To Other
NestBus
Devices
Termination Resistor
SMLSML
Controller
*1
*1
T1
T2
T3
T4
T1
T2
T3
T4
T1
T2
T3
T4
■ NestBus
*1. Internal terminating resistor is used when the device is at the end of a transmission line.
*2. Install shield cables to all sections and ground them at single point.
*2
FG

M-system SC100 Specifications

General

Brand	M-system
Model	SC100
Category	Controller
Language	English