SA380TX Local Configuration

All configuration of the logger can be carried out using the touchscreen display.  For ease of use, a USB keyboard can be plugged in to the port on the front of the logger.

This is highly recommended – it can be time consuming typing channel names in on the touchscreen.

To set up the logger, first the individual channels are configured, then the acquisition.

The inputs config tells the logger what is connected to each channel.  Once this is set, the logger can output the value that is being monitored in calibrated engineering units.

For instance, for points motor current, the logger would output a value in the range of 0-20A.

The acquisition config tells the logger what to log and when.

Digital inputs

Setup of digital inputs is straightforward.  The only information needed is channel name and whether the input is connected to a front or back contact of a relay 
(front = normally open, back = normally closed).

Navigate to:

Menu..Configuration..[enter passcode]..Digital

The following dialog is displayed:

“F” means front contact.  Selecting one of the channels and pressing “edit” allows the name and contact type to be changed.

Analogue inputs

First navigate to the analogue inputs dialog.

Menu..Configuration..[enter passcode]..Analogue

The following dialog is displayed:

The values shown on the buttons are updated in real time.  By default, the sensor type is set to “no sensor”, and the actual milliamp value at the 4-20mA input is shown.

Press one of the buttons to edit the channel.  The name of the channel can be changed, and the sensor type.

When naming the channels, it is suggested that the following conventions are used:

Force             F

Current          I

Points            W

Track             T

For instance, the motor current of 786 points would be given a name of “786 WI”, and 384 track current would be called “384 TI”

Sensor type

The TX is preconfigured with calibration settings for several sensor types.  (Further sensor types can be added by pressing the “New” button and following the instructions.)

Selecting LEM PCM20 and pressing “OK” then “Save” returns to the analogue inputs screen:

The input is showing –5.0A because there is no actual sensor connected to the input.

When the sensor is connected, it will present 4mA at the input, which corresponds to a motor current of 0A, and the logger will display 0.0A.

Acquisition – Acquire on change

Background

The principle of acquire on change is simple.  A sample is acquired when the measured value changes by more than a certain amount.  If there is no change, there is no sample acquired.

Consider the following waveform.  The acquired samples are shown as dots.

The waveform first changes at a fairly leisurely pace, then there is a spike.  Each time the input changes by a given percentage, a sample is acquired.

It can be seen that more data points are acquired around the spike.

Acquire-on-change is an excellent match for many railway applications.  Where there are long periods without much change, very little data is acquired.

Where there is more detail in the waveform, more points are acquired.

After the data has been acquired it is possible to go back and just “join the dots” and we have an accurate representation of the entire waveform, with the minimum amount of data logged.

Batching

It would be inefficient to save each sample (or push each sample to the server) individually.  This is particularly relevant when the waveform is changing quickly.

At present it takes approximately ten seconds to send a message to the server over GPRS.  If the waveform is changing quickly, the logger can be acquiring 100 samples per second.

It is clearly not possible or desirable to send each sample individually.

Two parameters are used to control the batching.  If the waveform is changing, the logger will wait until it stops, then a few seconds later will batch up the samples it has acquired during the change and save/send them.

This number of seconds is settable.

However if the waveform is continuously changing, albeit slowly, then there needs to be a backup plan to ensure that samples still get saved/sent.

Hence there is a second parameter which allows the user to set a maximum number of samples in the buffer.

Setting up acquire-on-change

Navigate to:

Menu..Configuration..Acquire-on-change

By default, all of the acquire-on-change is turned off.

To configure it on a channel, press the appropriate button on this dialog.

The following is then displayed:

Acquire-on-change is set as a percentage of full scale deflection (the maximum measured value for a channel).  In this case the channel is connected to a 0-600mA current clamp.

Hence 5% of this is 30mA.

All parameters can be set by pressing the appropriate buttons on this dialog.

Pressing the button marked “OFF” toggles the acquire-on-change to “ON”

Pressing “Save” stores the settings and activates the acquire-on-change for this channel.

384TI is now shown bold, with the acquire-on-change thresholds underneath.

Acquisition – Captures

In this mode the SA380TX behaves like an oscilloscope.

The principle is that a start trigger and an end trigger are set, and the TX records data between these two points.  The data is recorded to disk in a file, and sent to a central server as well if available.

Triggering and capture is very flexible; the TX can trigger on any digital channel or analogue level, and can log data from any of the analogue channels.

It can also be set to log data before and after the start trigger and end trigger events (this is called pretrigger and posttrigger).

Up to three analogue channels can be logged in each capture.

Up to 16 captures can be set up.  Captures all run completely independently of each other and can run simultaneously. They can also be associated together or “grouped”,

for example the Normal to Reverse capture from a set of points may be “grouped” with the Reverse to Normal capture from the same points.

In the above diagram, the TX has been set to capture an N-R point move.  It starts acquiring when the NKR drops, and finishes when the RKR picks.

Setting up captures using the touchscreen

Navigate to: Menu..Configuration..Triggered captures

The list of captures is shown.  At first this will be empty.

Press “New”.

Type the name of the new capture (eg 786 N-R) and press “Enter”.

The “Edit capture” dialog is shown.

Press the “Edit..” button next to Start Trigger.

The top three buttons are toggle / cycle buttons.  Pressing them repeatedly cycles through the types of trigger, channels and up/down.

For more details on how this dialog works, see “Trigger settings in detail” later in this document.

Press “Enter” when you are happy with the trigger settings.

Do the same for the end trigger (see above right).

Now set the channels to log by pressing the “Edit” button next to “Logged channels”.

Pressing each of the buttons toggles between “Yes” and “No”.  Press “Enter” to go back to the Edit Captures dialog.

Finally press “Capture Group” to assign this capture to a “group”.

All captures within the same group will appear as a single asset on your central monitoring server, hence it is important that Normal to Reverse,

and Reverse to Normal captures from the same end of points both belong to the same capture group.

All the capture details have now been entered.

To save these details, press the “Save” button.  This saves the changes and immediately sets the capture up in the logger.

If you press the “X” button at this point, the changes you have made will be discarded.

The N-R capture has now been set up successfully.

Depending on the start and end trigger settings, creating the R-N capture can be as simple as selecting the 786 N-R capture as shown, and press “Copy + reverse”.

The logger creates a new capture as follows:

Press “Save” to store this new capture.

Both captures have now been set up successfully.

Trigger settings in detail

The TX can be set to trigger on digital events or analogue threshold levels.  The thresholds or events can be from any of the input channels – they don’t need to be from the channels that are being logged.

By default the trigger will be an event trigger, digital channel 1, going DN.

Pressing the button currently marked “786 NWK” will cycle through the digital channels.

Pressing “DN” will change the direction of the action to “UP”.

Pressing “Pretrig” and “Post[trig]” opens dialogs allowing the pretrig/posttrig values to be entered.  These values are in milliseconds.

Pressing the “Event” button will change the type of trigger to a threshold level trigger (see over)

A keypad and a “level” textbox appears.

The threshold can be set by entering a value on the keypad.

Pressing the button currently marked “786 WI” cycles through the analogue channels.

Pressing “More than” changes the direction of the trigger to “Less than”.