A field device interface module comprising: a connector configured to operably couple to a computer, wherein the field device interface module is powered through the connector; a plurality of terminals (50, 52) operably coupleable to a field device; a protocol interface module coupled to the plurality of terminals and configured to generate signals in accordance with a process communication protocol; a controller coupled to the protocol interface module; a power supply module coupled to the plurality of terminals and coupled to the controller and operably coupled to the connector; and wherein the controller is configured: to measure a DC voltage across the plurality of terminals and to determine if the DC voltage exceeds a threshold, and cause the power supply module to provide power to the field device if the measured DC voltage is below the threshold by causing the power supply module to apply a current-limited voltage across the terminals; characterized in that the controller is further configured: to wait until a maximum field device startup time has elapsed and then determine if the field device is drawing current above a minimum current; and to cause the power supply module to reverse polarity of power provided through the terminals if the field device is not drawing current above the minimum current. a connector configured to operably couple to a computer, wherein the field device interface module is powered through the connector; a plurality of terminals (50, 52) operably coupleable to a field device; a protocol interface module coupled to the plurality of terminals and configured to generate signals in accordance with a process communication protocol; a controller coupled to the protocol interface module; a power supply module coupled to the plurality of terminals and coupled to the controller and operably coupled to the connector; and wherein the controller is configured: to measure a DC voltage across the plurality of terminals and to determine if the DC voltage exceeds a threshold, and cause the power supply module to provide power to the field device if the measured DC voltage is below the threshold by causing the power supply module to apply a current-limited voltage across the terminals; characterized in that the controller is further configured: to wait until a maximum field device startup time has elapsed and then determine if the field device is drawing current above a minimum current; and to cause the power supply module to reverse polarity of power provided through the terminals if the field device is not drawing current above the minimum current. to measure a DC voltage across the plurality of terminals and to determine if the DC voltage exceeds a threshold, and cause the power supply module to provide power to the field device if the measured DC voltage is below the threshold by causing the power supply module to apply a current-limited voltage across the terminals; characterized in that the controller is further configured: to wait until a maximum field device startup time has elapsed and then determine if the field device is drawing current above a minimum current; and to cause the power supply module to reverse polarity of power provided through the terminals if the field device is not drawing current above the minimum current. to wait until a maximum field device startup time has elapsed and then determine if the field device is drawing current above a minimum current; and to cause the power supply module to reverse polarity of power provided through the terminals if the field device is not drawing current above the minimum current.