Mobile hydraulic measuring equipment requirements correlate with ongoing improvements in machine technology (providing for example, a greater number of functions, shorter production cycles, and higher process precision) and with higher expectations with regards to inspection, testing, fault finding and documentation (such as documentation for final machine acceptance). Furthermore, measurements now need to include events and sizes that previously were of lesser importance or not sufficiently understood. Measuring equipment that is used in the design process, commissioning, maintenance, and service of mobile machinery therefore needs to provide a corresponding range of measurement options. In addition to a large range of functions, the main criteria for selecting this equipment include its flexibility (so it can be used for an extensive range of measurement tasks) and its user-friendliness.

Given that the quality of the data is only ever as good as the weakest link in the measurement chain, particular attention must be given to the quality of each of the sensors used, as their accuracy and dynamics are of significant influence. Prior to every measurement, it is mandatory to reconsider the set-up and the equipment’s settings to rule out systematic or random errors.

Understanding complexity is key to selection
Suitable measuring equipment is mainly geared to the specific measurement task. They can be used to for simple measurement tasks, such as gauging pressure, flow, and temperature, or for condition monitoring and more. HYDAC Electronic offers three different portable data recorders for all such jobs, including two new recorders.

On the basic end, the HMG 510 is suitable for simple measurement tasks. Two HYDAC Sensor Interface HSI transmitters can be connected, for example to measure pressure and temperature. The transmitters are automatically recognised by the HMG 510 so the user does not have to enter any manual settings.

In addition to normal measurement functions, the new portable data recorder HMG 2500 builds off the HMG 510 and can record measurement curves and event logs (for long-term measurements). Up to three HSI transmitters can be connected, so this equipment also has automated measurement operation with no manual settings required. An additional frequency input also is given, which can be used to record drive speeds.

High-end portable data recorder, the HMG 4000

While taking a curve recording measurement, a virtual “calculated” channel can also be displayed, for example for power measurement. Two independent triggers allow the user to record measurement curves that are controlled by events and are therefore highly specific. The measurement value memory can hold at least 100 individual curves with a total of 50 million values. An extensive range of useful tools, such as zoom, ruler and tracker (used for differential evaluations) allow curves to be analyzed immediately and simply. Measurements are displayed on a 3.5-in. color display with full graphics capability.

Launched earlier this spring, the high-end, hand-held measuring unit HMG 4000 is the new “flagship” of the HYDAC portable data recorder fleet, offering new measurement options, display and ease of use. Data is displayed on a high-resolution, color 5.7-in. touch screen. Like operating a smartphone, items are selected by tapping on them and areas on the screen are enlarged or reduced by pinching or spreading with two fingers.

The HMG 4000 gives technicians’ more flexibility in their measuring equipment. One proof of this is the number of sensors that can be connected. Up to 38 sensors at a time can be connected to the HMG 4000 and recorded. For the electrical connection a standard M12 connector is used. Eight connectors are provided to connect analog transmitters. These can be HSI transmitters to which the HMG automatically and fully synchronizes itself. Alternatively, other transmitters or components can also be connected, with a signal range from –10 to 50 V or 0 to 20 mA. This includes the signals of standard transmitters, e.g. 0 to 10 V or 4 to 20 mA and also signal values for proportional valves from –10 to 10 V. For this purpose, the HMG 4000’s parameters are set accordingly by the user.

Two digital input channels with a measurement range from 0.01 to 30,000 Hz are provided for the measurement of frequencies, times, drive speeds, pulses or PWM duty cycles.

Integrated sensor recognition

An additional connector is available to obtain data from sensors located in an existing CAN network on the machine side, such as J1939 or CANopen. A customised CAN parameter list is provided for the identification of these sensors, in which the measurement technician places the data one time. This input channel can also be used to stack sensors in connection with normal measurement tasks. In addition to the eight analog inputs, up to 28 signals from additional sensors can also be read in.

CAN network on HMG 4000

Various HCSI (HYDAC CAN Sensor Interface) sensors can also be connected. These are all recognized and read out by the HMG 4000 automatically.

The equipment is fully ready for measurement only seven seconds after being switched on and the measurement values of all connected sensors are shown to the user in a customisable display format. If requested, the respective minimum and maximum values and the progressive measurement can also be displayed.

In the tending graphs, the user gets initial qualitative information with regards to the dynamic response of the particular measured variable, for each input channel. Beyond this normal measurement function, the HMG 4000 offers a large number of additional measurement options and support functions.

The most demanding measurement mode certainly lies in the recording of measurement curves. The equipment can record individual curves, endless curves, event-controlled curves and event logs. For individual curves, one single measurement curve is recorded—which may be started manually and is frequently used in documentation-based measurement tasks.

In an endless recording, the curve continuously runs across the display window, like an oscilloscope display, and it can be stopped manually when needed. An event log is intended for recordings of measurement values over a longer period of time and that are recorded in tabular form.

Exact measurement of time-critical processes
Unlike the event log, event-controlled curves are ideal for measurement tasks that are intended to highlight a short time period in which a particular event takes place. This equipment function is predominantly used for fault finding or to find phenomena that were not originally expected, such as pressure peaks. The HMG 4000 user can use six individual triggers for this purpose, each of which can be linked with the others, enabling events to be defined with high precision. Ten input channels can also be recorded simultaneously with a top sampling rate of 100 ?s, allowing for nearly all time-critical processes in a machine or a system to be recorded. The internal data memory can record at least 500 individual measurement curves with a total of 4 billion measurement values. During recording of a curve, the individual signal curves can be scaled larger in each axis, measurement value and time, so that processes of interest can be observed in detail directly. Curves recorded completely can be analyzed quickly and easily afterwards. Various analysis tools are available for this, such as a “tracker” that can be used to determine the time or measurement value differences.

The user can save all of the equipment settings made for a particular measurement set-up with an individual name, and at a later point in time open this device set-up again. For external data transfer two USB interfaces are available. One is used to transfer data to a memory stick and the other is for bidirectional communication with a PC.

The evaluation software HMGWIN, which is included in the scope of delivery for the two new portable data recorders, provides customized visualisation, survey, annotation and storage of the measurement curves. The HMGWIN software’s features also include the option of converting measurement values to other data formats or even the fully automatic compilation of measurement reports in PDF format.