Some CLX definitions :

Major revision A module revision that is updated any time there is a functional change to the module.

Minor revision A module revision that is updated any time there is a change to the module that does not affect its function or interface

Coordinated system time (CST) Timer value which is kept synchronized for all modules within a single Control Bus chassis

ControlBus The backplane used by the 1756 chassis.

Input data - module returns only general fault and input data

CST timestamped input data - module returns input data with the value of the system clock (from its local chassis) when the input data changed

Full diagnostic input data - module returns input data, the value of the system clock (from its local chassis) when the input data changed, and diagnostic data (diagnostic modules only)

Rack optimization - the 1756-CNB module collects all digital input words in the remote chassis and sends them to the controller as a single rack image. This connection type limits the status and diagnostic information available

output data - owner controller sends the module only output data

CST timestamped fuse data - output data - owner controller sends the module only output data. Module returns fuse blown status with the value of the system clock (from its local chassis) when the fuse was either blown or reset

Full diagnostic - output data - owner controller sends the module only output data. Module returns diagnostic data and a timestamp of diagnostics

Scheduled output data - owner controller sends the module output data and a CST timestamp value

CST timestamped fuse data - scheduled output data – owner controller sends the module output data and a CST timestamp value. Module returns fuse blown status with the value of the system clock (from its local chassis) when the fuse was either blown or reset

· Full diagnostics - scheduled output data - owner controller sends the module output data and a CST timestamp value. Module returns diagnostic data and a timestamp of diagnostics

· Rack optimization - owner controller sends all digital outputwords to the remote chassis as a single rack image

Pulse TestPulse Test is a feature found on diagnostic output modules that canverify output-circuit functionality without actually changing the stateof the output load device. A short pulse is sent to the targeted outputcircuit. The circuit should respond as it would if a real change-of-command was issued, but the load device does not transition.TIP Consider the following when using the Pulse Test:

· Only use the test when the output state does transition for long periods of time. Normal diagnostics will catch faults if the outputs are

transitioning regularly.

· When first performing the pulse test, it is recommended that you verify the load will not transition. You should be at the actual load while the test is performed.

The Pulse Test can be used to perform a preemptive diagnosis ofpossible future module conditions. For example, you can use PulseTest to:

· detect a blown fuse before it happens. The Blown Fuse diagnostic can only be used when an output module is in the ON state. But it would useful to be made aware when operating conditions for a

module may cause a blown fuse. If you perform a pulse test on the module while the output is in the OFF state, the output point is commanded to be ON briefly, as described above. Although no diagnostic bits are set in the output data echo, the pulse test will report a failure because conditions when the point is ON indicate a blown fuse condition may occur

· detect a No Load condition with an output ON.The No Load diagnostic explanation) can only detect a fault (i.e. set the No Load bit)when an output point is in the OFF state. But you may find ituseful to be made aware when operating conditions for thatpoint may reveal a potential No Load condition.If you perform a pulse test on an output point while it is in theON state, the output point is commanded to be OFF briefly, asdescribed on The pulse test will report a failurebecause conditions when the point is OFF indicate the possibleabsence of a field device; in this case, though, the No Load bitwill not be set .Pulse Test is a service that needs to be executed from an RSLogix 5000program or the module properties page, using the pulse test tab andshould be verified with your load to make sure that there are no falsetransitions.

the electronic protection of the module has been designed to provide protection for the module from short circuit conditions. The protection is based on a thermal cutout principal. In the event of a short circuit condition on an output channel, that channel will limit the current within milliseconds after its thermal cutout temperature has been reached. Other channels could produce a false error on the output verify fault signal due to the supply dropping below the minimum detect level of 19.2V dc. The output channels that are affected by this phenomena will continue to operate as directed by the module master (CPU, Bridge, etc.) What this means is that the output verify fault signals of the other channels should be checked and reset if a short circuit on one channel occurs.

Configure Analog modules:

Notch FilterAn Analog-to-Digital Convertor (ADC) filter removes line noise in yourapplication for each channel.Choose a notch filter that most closely matches the anticipated noisefrequency in your application. Remember that each filter time affects theresponse time of your module. Also, the highest frequency notch filtersettings also limit the effective resolution of the channel.Important: 60Hz is the default setting for the notch filter.Use the table below to choose a notch filter setting.

Real Time Sampling

This parameter instructs the module to scan its input channels and obtain all available data. After the channels are scanned, the module multicasts that data.During module configuration, you specify a Real Time Sampling (RTS)period and a Requested Packet Interval (RPI) period. These features bothinstruct the module to multicast data, but only the RTS feature instructs themodule to scan its channels before multicasting.

Digital Filter

The digital filter smooths input data noise transients on each input channel. This value specifies the time constant for a digital first order lag filter on the input. It is specified in units of milliseconds. A value of 0disables the filter.The digital filter equation is a classic first order lag equation. Using a step input change to illustrate the filter response, as shown below, you can see that when the digital filter time constant elapses, 63.2% of the total response is reached. Each additional time constant achieves 63.2% of the remaining response.Important: The digital filter is only available in applications using floatingpoint mode.

Yn = Yn-1 + (Xn – Yn-1)[D t]D t + TAYn = present output, filtered peak voltage (PV)Yn-1 = previous output, filtered PVDt = module channel update time (seconds)TA = digital filter time constant (seconds)Xn = present input, unfiltered PV

Deadband

allows the process alarm status bit to remain set, despite the alarm condition disappearing, as long as the input data remains within the deadband of the process alarm.

Rate Alarm

The rate alarm triggers if the rate of change between input samples for each channel exceeds the specified trigger point for that channel.

For example, if you set the 1756-IF16 (with normal scaling in Volts) to a rate alarm of 1.0 V/S, the rate alarm will only trigger if the difference between measured input samples changes at a rate > 1.0 V/S. If the module’s RTS is 100 ms (i.e. sampling new input data every 100ms) and at time 0, the module measures 5.0 volts and at time 100ms measures 5.08 V, the rate of change is (5.08V - 5.0V) / (100mS) = 0.8 V/S. The rate alarm would not set as the change is less than the trigger point of 1.0V/s.

If the module’s RTS is 100 ms (i.e. sampling new input data every 100ms) and at time 0, the module measures 5.0 volts and at time 100ms measures 5.08 V, the rate of change is (5.08V - 5.0V) / (100mS) = 0.8 V/S. The rate alarm would not set as the change is less than the trigger point of 1.0V/s.If the next sample taken is 4.9V, the rate of change is (4.9V-5.08V)/ (100mS)=-1.8V/S. The absolute value of this result is > 1.0V/S, so the rate alarm will set. Absolute value is used because rate alarm checks for the magnitude of the rate of change being beyond the trigger point, whether a positive or negative excursion.

Hold for Initialization

Hold for Initialization causes outputs to hold present state (hold the output signal unchanged) until the value commanded by the controller matches the value at the output screw terminal within 0.1% of full scale, providing a bumpless transfer.If Hold for Initialization is selected, outputs will hold if any of the threeconditions occur:· Initial connection is established after power-up· A new connection is established after a communications fault occurs· There is a transition to Run mode from Program stateThe InHold bit for a channel indicates that the channel is holding.