A process variable transmitter, comprising: a processor configured to receive an input signal indicative of a sensed process variable and outputting a digital signal indicative of the input signal; a digital-to-analog (D/A) converter configured to receive the digital signal and configured to convert it to an analog signal; the process variable transmitter being characterized by: a loop control component configured to receive the analog signal and configured to control a two-wire process control loop based upon a voltage generated across a resistive element coupled in series with the two-wire process control loop to provide a transmitter output signal indicative of the analog signal, the transmitter output signal varying, on-scale, between a first signal level and a second signal level; and a loop diagnostic component being configured to compare a first signal value indicative of the analog signal with a second signal value indicative of the transmitter output signal to determine whether the transmitter output signal includes an on-scale error and is configured to responsively output an error indicator to the processor; wherein the analog signal output by the D/A converter comprises an analog voltage, wherein the loop diagnostic component includes an analog comparator being configured to compare the analog voltage comprised in the analog signal, as the first signal value with the voltage across the resistive element, as the second signal value. a processor configured to receive an input signal indicative of a sensed process variable and outputting a digital signal indicative of the input signal; a digital-to-analog (D/A) converter configured to receive the digital signal and configured to convert it to an analog signal; the process variable transmitter being characterized by: a loop control component configured to receive the analog signal and configured to control a two-wire process control loop based upon a voltage generated across a resistive element coupled in series with the two-wire process control loop to provide a transmitter output signal indicative of the analog signal, the transmitter output signal varying, on-scale, between a first signal level and a second signal level; and a loop diagnostic component being configured to compare a first signal value indicative of the analog signal with a second signal value indicative of the transmitter output signal to determine whether the transmitter output signal includes an on-scale error and is configured to responsively output an error indicator to the processor; wherein the analog signal output by the D/A converter comprises an analog voltage, wherein the loop diagnostic component includes an analog comparator being configured to compare the analog voltage comprised in the analog signal, as the first signal value with the voltage across the resistive element, as the second signal value. a loop control component configured to receive the analog signal and configured to control a two-wire process control loop based upon a voltage generated across a resistive element coupled in series with the two-wire process control loop to provide a transmitter output signal indicative of the analog signal, the transmitter output signal varying, on-scale, between a first signal level and a second signal level; and a loop diagnostic component being configured to compare a first signal value indicative of the analog signal with a second signal value indicative of the transmitter output signal to determine whether the transmitter output signal includes an on-scale error and is configured to responsively output an error indicator to the processor; wherein the analog signal output by the D/A converter comprises an analog voltage, wherein the loop diagnostic component includes an analog comparator being configured to compare the analog voltage comprised in the analog signal, as the first signal value with the voltage across the resistive element, as the second signal value.