Application note

Serial RS-422/485 wiring

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Description

SEM products with a serial interface may be connected to a system in either single or party (multidrop) configuration.

The key differences to note between Lexium MDrive and MDrive/MForce products is that with Lexium products the interface is galvanically isolated. MDrive/MForce products:

  • are not isolated
  • have a 100Ω resistor in series with communications ground

This variance necessitates a change when wiring multidrop systems to prevent recirculating currents: See this Application Note: Recirculating currents in RS-422 multi-drop systems

Applicable

  • Lexium MDrive
  • MDrive Linear Actuator
  • MDrive Plus
  • MForce

Requirements

Details

Lexium MDriveMDrive

Single interface

Wiring diagram:  Full duplex (4-wire) only

lnd422single
Figure 1: Single Lexium MDrive full duplex point-to-point configuration

 Notes and checkpoints

  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ground is galvanically isolated on the Lexium MDrive
  • If using a pre-made cable, verify wire color to pin location – when in doubt, ring it out

Party mode interface

Party mode is an advanced communications configuration requiring a working knowledge of the ANSI/TIA/EIA-422 and TIA/EIA-485 standards, as well as SEM MDrive products and the MCode programming and control language.

lexium-mdrive-422-multipoint
Figure 2: Lexium MDrive RS-422 multipoint system, bus and stub configuration

Single interface

Wiring diagram:  Full duplex (4-wire) only

Single MDrivePlus/MForce - full duplex connection
Figure 1: Single MDrivePlus/MForce – full duplex point-to-point connection

  Notes and checkpoints

  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ground is galvanically isolated on the Lexium MDrive
  • If using a pre-made cable, verify wire color to pin location – when in doubt, ring it out.

Party mode interface

Party mode is an advanced communications configuration requiring a working knowledge of the ANSI/TIA/EIA-422 and TIA/EIA-485 standards, as well as SEM MDrive products and the MCode programming and control language. The diagram below shows a bus and stub type network configuration, MDrive/MForce RD and RL style connectors provide an additional signal contact point for daisy-chain configurations.

MDrive/MForce RS-422 multipoint network
Figure 2: MDrive/MForce RS-422 multipoint network, bus and stub configuration

 

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