Multiple port SCADA multidrop multiplexer combines multiple polling systems and protocols over one network

  • Multiplex up to four separate polling systems through one communications network
  • Each port can have a different protocol and application (SCADA, Loadflow, AMR, etc.)
  • Supports VanComm and Conitel protocols, DNP, Modbus, non-protocol ASCII
  • Each port can be set to a different speed
  • Host to remote port speed conversion
  • Multiplex over radios, modems, DSUs, etc.
  • Use for SCADA RTU control, metering, load management, etc.
  • Power control and RS-232 Access Switch functions are suported
  • Synchronous or asynchronous composite
  • Internal spread spectrum radio option
  • Operating temperature range of -40 to +70 C
  • Stand-alone, rack mount, or wall mount


Port Specifications
Network Specifications
Operating Modes
Indicators (front panel)
Network Management Port
Network Management Port Commands



The SCADA Multidrop Mux (SMD-VC) is designed for sharing one multidrop radio, modem or DSU system with 2 or more multidrop polling systems. The SMD-VC supports byte oriented asynchronous data plus VanComm and Conitel protocols. With the SMD-VC, one multidrop network can support multiple protocols and systems, such as DNP, Modbus, VanComm, Conitel, etc. RTUs can be polled on a multidrop system at the same time other polling takes place for load management, automatic meter reading, etc. The SMD-VC is 50 to 75% less costly than duplicate and parallel multidrop radio, modem, or digital systems. And that savings is just the upfront purchase cost. After factoring the cost of licensing radio systems, installing and maintaining equipment, savings are even greater.

The composite of the mux can be synchronous with speeds up to 128 Kbps, or asynchronous, with speeds up to 115.2 Kbps. Ports can be set at speeds up to 57.6 Kbps. The composite and ports are RS232/EIA561. The ports can be used with just 3 wires (send, receive and ground) or with full RTS/CTS and Carrier Detect control. RS422 adapters are available for the ports.

In addition to multiplexing polling protocols, the SMD-VC can be used as an Ethernet bridging device, Access Switch, or power control device. For low bandwidth Ethernet applications, Ethernet can be added using DCB’s SCADA Multidrop EtherBridge. The Access Switch function allows terminal control of remote serial device management ports (UPS, radios, meters, etc.) The DCB APS-01 unit provides for a remote power control switch.

The SMD-VC sends data from host terminal ports to the remote units as soon as the data comes into the host ports. All the remote SMD-VCs receive the data. The host SMD-VC is also continually checking the remote SMD-VCs to retrieve any data from remote ports. The SMD-VC unit also keeps together blocks of data coming into the ports. This insures that polling protocols such as Modbus RTU will work successfully with the SCADA Multidrop Mux.

Setup of the SMD-VC is simple, using a terminal or PC connected to the management port. Easy to use English command menus are used to set the number of remote drops, the port speeds, port IDs (if desired), the drop number for the remote SCADA multiplexers, sync or async network operation, and control lead timing parameters. The management port can also be used to check system operation, including port activity, link errors, port monitoring, etc. The management port commands are short, simple and comprehensive. Drop SMD-VC multiplexers can be added as transparent devices, activated only when a host SMD-VC is installed. This makes installation much less stressful, since the SMD-VCs can be installed without taking an entire system out of service.

Indicators (front panel)
Power, Acitivity, Receive Error, Modem Ready, Port 1 Setup,Loopback

Rear view of SMD-VC Multiplexer


How to Order

SMD-VC SCADA-Mux Pricing:
SMD-VC SMD-VC SCADA-MUX Multiplexer $ 2125
SMD-VC-DSU Internal 56/64 Kbps DSU option for SCADA-MUX $ 325

Data Comm for Business Inc.
2949 County Road 1000 E
Dewey, Il 61840
Voice: 217-897-6600
Toll Free: 800-4-DCB-NET
Toll Free: 800-432-2638
Email: Contact Page
Fax: 217-897-8023
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