An I/O module circuit for use in an industrial control system comprising: a housing; terminals supported by the housing for receipt of electrical power to be controlled by the I/O module circuit; and a circuit contained in the housing providing: at least one field effect transistor having a source and drain in series between the terminals to control current flow through the terminals according to a first signal received by a gate of the field effect transistor; at least one transformer coupled isolator receiving input electrical power referenced to a second signal at a controller side to provide output electrical power referenced to the first signal at a field side but floating with respect to the second signal; a first resistor connected between the gate of the at least one field effect transistor and a field-side data output of the at least one transformer coupled isolator providing the first signal such as to connect the at least one transformer coupled isolator to the gate via the first resistor; a transistor having a base connected between the first resistor and the gate, an emitter connected between the first resistor and the field-side data output, and a collector connected to ground via a second resistor and to a field-side data input of the at least one transformer coupled isolator, wherein the transistor is configured to detect fault conditions of the at least one field effect transistor in that a lowering of a voltage on the base of the transistor resulting from a fault occurring in the at least one field effect transistor causes a conduction of the transistor raising the voltage of a third signal at the field-side data input for providing an indication at the controller side that the at least one field effect transistor is in a fault condition; and a releasable electrical connector supported by the housing receiving the second signal indicating a desired control of electrical power at the terminals of the I/O module. a housing; terminals supported by the housing for receipt of electrical power to be controlled by the I/O module circuit; and a circuit contained in the housing providing: at least one field effect transistor having a source and drain in series between the terminals to control current flow through the terminals according to a first signal received by a gate of the field effect transistor; at least one transformer coupled isolator receiving input electrical power referenced to a second signal at a controller side to provide output electrical power referenced to the first signal at a field side but floating with respect to the second signal; a first resistor connected between the gate of the at least one field effect transistor and a field-side data output of the at least one transformer coupled isolator providing the first signal such as to connect the at least one transformer coupled isolator to the gate via the first resistor; a transistor having a base connected between the first resistor and the gate, an emitter connected between the first resistor and the field-side data output, and a collector connected to ground via a second resistor and to a field-side data input of the at least one transformer coupled isolator, wherein the transistor is configured to detect fault conditions of the at least one field effect transistor in that a lowering of a voltage on the base of the transistor resulting from a fault occurring in the at least one field effect transistor causes a conduction of the transistor raising the voltage of a third signal at the field-side data input for providing an indication at the controller side that the at least one field effect transistor is in a fault condition; and a releasable electrical connector supported by the housing receiving the second signal indicating a desired control of electrical power at the terminals of the I/O module. at least one field effect transistor having a source and drain in series between the terminals to control current flow through the terminals according to a first signal received by a gate of the field effect transistor; at least one transformer coupled isolator receiving input electrical power referenced to a second signal at a controller side to provide output electrical power referenced to the first signal at a field side but floating with respect to the second signal; a first resistor connected between the gate of the at least one field effect transistor and a field-side data output of the at least one transformer coupled isolator providing the first signal such as to connect the at least one transformer coupled isolator to the gate via the first resistor; a transistor having a base connected between the first resistor and the gate, an emitter connected between the first resistor and the field-side data output, and a collector connected to ground via a second resistor and to a field-side data input of the at least one transformer coupled isolator, wherein the transistor is configured to detect fault conditions of the at least one field effect transistor in that a lowering of a voltage on the base of the transistor resulting from a fault occurring in the at least one field effect transistor causes a conduction of the transistor raising the voltage of a third signal at the field-side data input for providing an indication at the controller side that the at least one field effect transistor is in a fault condition; and a releasable electrical connector supported by the housing receiving the second signal indicating a desired control of electrical power at the terminals of the I/O module.