Removable terminal block assembly that permits an I/O base to operate in simplex mode or duplex mode

1. An I/O device comprising:

an I/O base having first and second ports for receiving at least a portion of a terminal block assembly;

at least two I/O modules supported on the I/O base; and

a duplex terminal block assembly supported on the I/O base and at least partially received in each of the first and second ports;

wherein the at least two I/O modules include a first I/O module and a second I/O module coupled to the duplex terminal block assembly in parallel; and

wherein the duplex terminal block assembly includes a terminal block base and a terminal block supported on the terminal block base, the terminal block base having a width that is greater than a width of the terminal block.

2. The I/O device of claim 1 , wherein the duplex terminal block assembly includes connectors for connecting to a field device.

3. The I/O device of claim 2 , wherein the duplex terminal block assembly includes conductive structures for coupling the connectors with each of the first and second I/O modules.

4. The I/O device of claim 1 , wherein the width of the duplex terminal block base is twice the width of the terminal block.

5. The I/O device of claim 4 , wherein the duplex terminal block is centered along the width of the terminal block base.

6. The I/O device of claim 1 , wherein the I/O base includes a third port for receiving at least a portion of a terminal block assembly, and further comprising:

a third I/O module supported on the I/O base; and

a simplex terminal block assembly received in the third port and electrically coupled to the third I/O module.

7. The I/O device of claim 6 , wherein the simplex terminal block assembly has a width that is half the width of the duplex terminal block assembly.

8. An I/O device comprising:

an I/O base having a plurality of ports for receiving at least a portion of a terminal block assembly, each port adapted for coupling one of a plurality of I/O modules to a terminal block assembly;

first, second and third I/O modules supported on the I/O base;

a duplex terminal block assembly received in at least two ports associated with the first and second I/O modules; and

a simplex terminal block received in a port associated with the third I/O module.

9. The I/O system of claim 8 , wherein the duplex terminal block assembly includes a terminal block base portion having connectors for coupling with two ports of the I/O base, and a terminal block extending from the terminal block base portion and having connectors for connecting to an associated field device.

10. The I/O system of claim 9 , wherein the terminal block base portion has a width such that it is at least partially received in each of the at least two ports associated with the first and second I/O modules when installed in the I/O base.

11. The I/O system of claim 10 , wherein the duplex terminal block includes conductive structures for coupling each of the at least two I/O modules in parallel to the connectors.

12. The I/O system of claim 8 , wherein the duplex terminal block assembly includes a terminal block base and a terminal block supported on the terminal block base.

13. The I/O device of claim 12 , wherein the duplex terminal block base has a width that is twice the width of the terminal block.

14. The I/O device of claim 13 , wherein the duplex terminal block is centered along the width of the terminal block base.