DM7 Programmable Resolver Decoder Single-Turn, Single-Channel

The most versatile resolver-to-digital decoder

Model DM7-xxx00-010

• Fully absolute position, no loss of position under any situation
• Incredibly small size; only 9 sq.in. panel space
• Full-scale programmable zero offset for easy set-up
• Programmable resolution; 20-4096 counts-per-turn
• Front panel selectable output formats: BCD, Binary, or Gray Code
• Built-in PC sync circuit permits interface to any PLC
• Built-in digital tach and over-, under-speed switch
• Direction output and zero marker pulse
• Self-diagnostics with fault output
• Optically isolated outputs
• Highly noise immune ratiometric tracking converter
• Extremely rugged and reliable resolver as position transducer

Principle of Operation

The DM7 series resolver to digital decoder provides an absolute encoder system in conjunction with any one of AVG Automation's single turn resolvers. As shown in the diagram on the next page, the resolver rotor winding is excited from a reference sinusoidal generator inside the DM7 unit. The ana­log output signals from the resolver stator windings, after sig­nal conditioning in the buffer amplifiers, are decoded to digi­tal format in the ratio in etrictracking converter. The zero‑off­set entered from the front panel keypad is continuously added to this digital value. The offset digital data is scaled, converted to the digital format as selected from the keypad and displayed on the front panel of the unit. The position information is also made available in a parallel format for external devices, such as PLC remote displays, etc.

Programmable Full-Scale Offset for Easy Set-Up

The resolver can be mounted on the machine without any concern for mechanically aligning the resolver zero to the machine zero. Once the resolver is coupled to the machine shaft, the only thing you have to do is to bring the machine to a known position, say home position, and set an offset number from the front panel keypad until the display reads zero position. This is especially useful during initial start up in that it reduces the set up time. The offset can also be used to compensate for any machine wear.

Programmable Resolution: 20-4096 Counts­per-Turn

The programmable scale factor feature provides you the flexibility of selecting the resolution in the field. Now you do not have to worry about defining the resolution at the time of ordering the unit. The scale factor can be programmed from the front panel and can be any number between 19 and 4095 resulting in resolution of 20 to 4096 counts per turn. This feature allows you to scale the position to desired engineering units (inches, mm, etc.), if required.

Front-Panel-Selectable Output Formats: BCD, Binary, or Gray Code 

The DM7 is an extremely versatile resolver to digital decoder. Now you do not have to define the output format at the time of ordering the unit. Depending upon your application, the output format such as BCD, Natural Binary, or Gray code can simply be selected from the front panel keypad. This means one unit for various applications.

Built-in PC synchronization

PC synchronization is built in as standard in DM7 resolver-to digital decoder. Depending upon the application it can be selected from the front panel keypad to operate with or without PLC synch circuit. When selected to operate with PLC synch circuit, it provides an error-free method of interfacing BCD or binary position data from the decoder to any PLC in the market. Upon receipt of a data transfer command from the PLC the stable data is latched and made available to the PLC. When selected to operate without PLC synch circuit (transparent or Microfreeze mode), the position data is continuously updated. At the data transfer command from a microcomputer, the data is latched for 100 ±10 ps to enable the microcomputer to read the information.

Self-Diagnostics with Fault Output

The DM7 is provided with an internal self-check circuit that continuously monitors if the microprocessor is not in reset, input 120 VAC power, DC power supplies, resolver cable, and output enable circuit. In case a fault occurs in any one of the above critical functions, the unit goes into fault mode and a transistor output changes state from ON to OFF. For failsafe operation, the fault output is ON for normal operation and turns OFF when a fault occurs. During the fault mode all outputs are disabled automatically.

High Noise Immune Circuitry 

The ratiometric tracking converter technique employed for resolver-to digital decoding provides the best protection against electrical noise generated by power line transients and varying ground potentials. This decoding method is inherently immune to temperature changes and line frequency variations. The optical isolation adds an additional layer of protection against electrical noise and enhances the environmental integrity of the system.

Built-in Tachometer & Over/Under Speed Switch 

The shaft RPM is continuously displayed on the front panel. Two additional outputs, one over-speed and the other under-speed, are provided. The reference speed values are entered from the front panel.

Program Security

A supervisory input is needed to make any changes to the program to protect against unauthorized tampering.

Rugged and Reliable Resolver as Position Transducer

The DM7 series of resolver decoder combines the ruggedness of a resolver and reliability of an advanced solid-state control. The rugged, heavy-duty NEMA 13 IP54 resolver can be mounted on a machine in any hostile industrial environment such as mechanical shock vibrations, extreme humidity and temperature changes, oil mist, coolants, solvents, etc. And the resolver-to-digital decoder can be mounted up to 2500 feet away in a control panel.