Toshiba MBP-100 Manual De Usuario

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6.  RS485 Port Electrical Interfaces 
In order to ensure appropriate network conditions (signal voltage levels, etc.) 
when using the gateway’s RS485 port, some knowledge of the network 
interface circuitry is required.  Refer to Figure 6 for a simplified network 
schematic of the RS485 interface circuitry.  Note that the “Shield” terminal has 
no internal connection: its purpose is simply to provide a cable shield chaining 
location between devices.  The shield is then typically connected to ground at 
one location only. 
 
Figure 6: RS485 Interface Circuitry Schematic 
 
 
Figure 7 details the specific network connections to the RS485 terminal block. 
 
 
 
A
B
Signal Ground
Shield
 
Figure 7: RS485 Terminal Block Connections