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FAQ
FAQs About RS-422 / 485

 
What is the different between RS-485 and RS-422?
 
RS-422 uses 2 wires for simplex transmission. RS-485 can use 2 wires for half duplex transmission. Full duplex systems are implemented using 4 wires. Both RS422 and RS485 can be used in multidrop configurations however precautions must be taken to prevent more than one transmitter being active on the same bus at once.
 
What is the different between Data-control and RTS-control?
 
Data-control: The data flow starts on the first bit. RTS-control: The data flow is controlled by handshaking. RTS (request to send) and CTS (Clear to send).
 
Can I use MD-45 instead of MD-42 and MD-44?
 
The compatibility of MD-(MA)-42, MD(MA)-44 and MD(MA)-45 The older units called MD(MA)-42, and MD(MA)-44 are replaced by MD-45. If they are compatible depends on the way to control the data flow. MD-42, MA-42 and MA-49 controlled by RTS (Request To Send) signal or in RS-422 transmission the transmitter can be set always active. MD-44, MA-44 and MA-47 are controlled only by data flow. In MD-45, MA-45 can the data direction be controlled by data flow or RTS. The new units (MD-45) that are produced after jan. 2003 has the transmitter always active function. Note! The function, transmitter always active, is only for the RS-422 (4-wire).

The new function in MD-45 works from serial number:
MD-45 AC 2668
MD-45 115VAC 139
MD-45 LV 3012
MD-45 LV temp 32
MA-45 AC 2414
MA-45 DC 74