Connect Tech Blue Heat/PCI PCI Serial Communications Manual De Usuario

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Blue Heat/PCI User’s Manual, Connect Tech Inc. 
 
 
31  
Revision 
0.11 
Appendix C: RS-422/485 Line Interface 
For information on how to configure your RS-422/485 interface, find your specific Blue 
Heat/PCI model below:  
 
Blue Heat/PCI RS-422/485  
You can order the Blue Heat/PCI RS-422/485 adapter with all ports RS-422/485 or a 
combination of RS-422/485 and RS-232.  The RS-422/485 electrical interface is a reliable high-
speed serial link that offers superior noise immunity and multi-drop network connectivity.  The 
RS-422/485 electrical interface is also a superset of the RS-422 electrical interface. The Blue 
Heat/PCI RS-422/485 offers full RS-422/485 support in hardware. The modes are as follows: 
Full Duplex Mode 
In this mode, TxD & RxD are active all the time. This mode is typically used in point to point 
situations much like RS-232. 
 
Half Duplex Mode 
In this mode the TxD line driver is enabled only when data is transmitted and RxD is disabled 
when data is being transmitted. This mode is typically used in either point to point "2 wire" 
connections OR in multi-drop "2 wire" bus connections. 
Multi-drop Slave Mode 
In this mode the TxD line driver is enabled only when data is transmitted and RxD is enabled all 
the time. This mode is typically used in multi-drop "4 wire" connections. 
Line Bias/Termination 
On the Blue Heat/PCI RS-422/485 the RS-422/485 receivers are biased high through fixed 
resistors.  Please refer to 
for a partial schematic. 
 
Universal Blue Heat/PCI RS-422/485  
Universal Blue Heat/PCI RS-422/485 adapters offer full RS-422/485 support in hardware like 
the other Blue Heat/PCI RS-422/485 models. The modes include full duplex, half duplex, and 
multi-drop slave.  Universal Blue Heat/PCI RS-422/485 adapters offer the following additional 
functionality: 
 
Tri-state Control 
Universal Blue Heat/PCI RS-422/485 adapters allow you to tri-state the line drivers on power 
up.  To tri-state the drivers on power up please ensure there is no jumper installed across the pins 
on jumper block JI.  Refer to 
 for the location of J1. 
Line Bias/Termination 
On the Universal Blue Heat/PCI RS-422/485 the RS-422/485 receivers are biased high through 
fixed resistors. Please refer to 
 for a partial schematic.