A process combustion control system comprising: a combustion source, a source of fuel and a source of air, said combustion source is operably coupled to said source of fuel and said source of air, the combustion source being configured to provide combustion gasses through a flue; a combustion controller coupled to at least one of the source of fuel and source of air; an in situ flue gas analyzer comprising: a probe extendable into a flue, the probe having a measurement cell providing a signal responsive to a concentration of a gas within the flue; a controller coupled to the probe and configured to provide an output based on the signal from the measurement cell; a first media access unit coupled to the controller and operably coupleable to a first process communication link, the first media access unit being configured to communicate in accordance with an all-digital process communication protocol over the first process communication link; a second media access unit coupled to the controller and operably coupleable to a second process communication link, the second media access unit being configured to communicate in accordance with a second process communication protocol that is a hybrid process communication protocol which is different than the all-digital process communication protocol, over the second process communication link; and wherein the first and second media access units (54, 56) are enabled simultaneously; wherein the in situ flue gas analyzer is coupled to the combustion controller and disposed to sense a concentration of a gas of interest within the flue and convey process information related to the concentration to the combustion controller in accordance with the all-digital process communication protocol; and wherein the in situ flue gas analyzer is communicatively coupled to a second device and communicates with the second device, in accordance with the second process communication protocol different than the all-digital process communication protocol, wherein communication with the combustion controller and the second device occurs substantially simultaneously. a combustion source, a source of fuel and a source of air, said combustion source is operably coupled to said source of fuel and said source of air, the combustion source being configured to provide combustion gasses through a flue; a combustion controller coupled to at least one of the source of fuel and source of air; an in situ flue gas analyzer comprising: a probe extendable into a flue, the probe having a measurement cell providing a signal responsive to a concentration of a gas within the flue; a controller coupled to the probe and configured to provide an output based on the signal from the measurement cell; a first media access unit coupled to the controller and operably coupleable to a first process communication link, the first media access unit being configured to communicate in accordance with an all-digital process communication protocol over the first process communication link; a second media access unit coupled to the controller and operably coupleable to a second process communication link, the second media access unit being configured to communicate in accordance with a second process communication protocol that is a hybrid process communication protocol which is different than the all-digital process communication protocol, over the second process communication link; and wherein the first and second media access units (54, 56) are enabled simultaneously; a probe extendable into a flue, the probe having a measurement cell providing a signal responsive to a concentration of a gas within the flue; a controller coupled to the probe and configured to provide an output based on the signal from the measurement cell; a first media access unit coupled to the controller and operably coupleable to a first process communication link, the first media access unit being configured to communicate in accordance with an all-digital process communication protocol over the first process communication link; a second media access unit coupled to the controller and operably coupleable to a second process communication link, the second media access unit being configured to communicate in accordance with a second process communication protocol that is a hybrid process communication protocol which is different than the all-digital process communication protocol, over the second process communication link; and wherein the first and second media access units (54, 56) are enabled simultaneously; wherein the in situ flue gas analyzer is coupled to the combustion controller and disposed to sense a concentration of a gas of interest within the flue and convey process information related to the concentration to the combustion controller in accordance with the all-digital process communication protocol; and wherein the in situ flue gas analyzer is communicatively coupled to a second device and communicates with the second device, in accordance with the second process communication protocol different than the all-digital process communication protocol, wherein communication with the combustion controller and the second device occurs substantially simultaneously.