RS-232C/RS-485 Converters, RS-485 Repeaters

The A1000 and A2000 series converter boxes convert RS-232 communication signal levels to the correct electrical signals required by RS-485. The RS-485 communications standard is recommended when many SCM9B modules, or other addressable devices, must be connected to a host computer over long distances. The A1000 and A2000 converters allow communications bus lengths up to 4,000 feet and data rates up to 115kbps using one twisted pair of wires.

The RS-485 standard allows for bidirectional data on the same pair of wires. Therefore, some means of arbitrating the data direction is required. The A1000 and A2000 automatically control the bus direction without external handshaking signals from the host. Host software written for half-duplex RS-232 may be used without modification, RS-485 bus control is completely transparent to the user.

The A1000 and A2000 can also operate as repeaters for RS-485. Repeaters are required to extend communications bus lengths or to allow more than 32 RS-485 devices to be connected to a communications bus. A repeater simply reamplifies, or boosts, existing RS-485 signals transmitted over long distances.

Product Availability
Usually stock to 2-3 weeks

Dimensions & Accessories


  • Completely Transparent to Host Software
  • No External Flow Control Signals Required
  • Optically-Isolated Bidirectional Data Flow
  • Standard Data Rates: 300 to 115kbps
  • Automatic Internal RS-485 Bus Supervision
  • Networking up to 4,000 Feet
  • CE Compliant

Block Diagram

SCM9B-A1000/A2000 block diagram


Due to resource constraints on my computer, I'm unable to open the three dimensional CAD models provided on your website. Does Dataforth provide two demensional CAD models for download as well?
Two dimensional CAD models can be generated upon customer request. Please contact Customer Service for assistance.
How does the load resistance of a module affect the noise at the output?
Noise at the output of a module is independent of load resistance.
How do I convert an RMS voltage to its corresponding peak voltage?
To convert an RMS voltage to its corresponding peak voltage, you simply take the RMS voltage value and multiply it by the square root of 2, or roughly 1.414. For example, 1500Vrms corresponds to a peak voltage of 1500 * 1.414 = 2121 Vp
If the input range of my signal conditioner is -1V to +1V and the output range is 0 to 10V, does this mean that it ignores polarity?
A signal conditioner with these I/O ranges does not mean that the module ignores the polarity of your voltage input. The output of voltage input modules are scaled linearly, meaning an input of -1V would correspond to an output of 0V, an input of 0V would correspond to an output of 5V, an input of +1V would correspond to an output of 10V, and so on.
Analog Devices announced a last time buy and discontinuance of their signal conditioning modules. Can I replace them with Dataforth signal conditioning modules?
Yes, in general, Dataforth signal conditioning modules are a direct replacement for all Analog Devices signal conditioning modules. e.g. "SCM5B35-xx: Linearized 4-Wire RTD Input Modules" will replace Analog Devices "5B35: Isolated 4 Wire RTD Input Signal Conditioning Module". Please note that Dataforth signal conditioning modules are RoHS II compliant.
Can Dataforth provide calibration reports for modules I purchased?
Yes we can provide calibration reports for the modules that you purchased. You can either a) visit to search for Test Report Datasheets by Serial Number or b) you can send us a list of model numbers and their serial numbers to

Custom Modules

Below is a list of existing custom modules. If you don't see a module matching your target specifications, contact Customer Service and Application Support to discuss design guidelines and design feasibility. Customer Service and Application Support can be reached at or +1-800-444-7644.
* ... Status Codes: PR = Production, PT = Prototypes, QU = Quoted

We want your feedback!

We are interested in your feedback regarding our products. Please let us know what you think and if you have any questions regarding the SCM5B32 and how this product could apply to your application. Your feedback is very valuable to us and very much appreciated.

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