If measurement signals need to be referenced over time with each other for processing and analysis, they must be recorded synchronously.
All SomatXR modules can be synchronized among themselves. This ensures simultaneous measurement on all channels. All the analog‑digital converter rates, measuring rates and bridge excitation voltages are also synchronized.
To achieve a precise reference over time, the applicable channels must be parameterized with the same filter settings. No automatic runtime correction is carried out. The filter runtimes are shown in the data sheet. After booting and successful synchronization, the system LED shows green. If synchronization is disturbed, or not yet established, the system LED shows orange.
Time stamps are appended to the measured values in the following format:
Feature | PTPv2 | NTP | FireWire |
---|---|---|---|
Synchronization with other devices | QuantumX (B series)
SomatXR CX23-R |
Quantum X MGCplus other |
QuantumX |
Maximum distance between modules | 100 m | 100 m | 5 m (40 m with FireWire extender, 500 m via optical fiber) |
Number of modules | Unlimited | Unlimited | 24 |
Accuracy | < 1 µs | < 10 ms | < 1 µs |
Settling time | Immediate | approx. 2 hrs during start approx. 10 min during restart |
Immediate |
Master | External PTP time-server
MX Module CX23-R |
External SyncMaster | MX module |
Voltage supply | None | None | 1.5 A looped through |
Each SomatXR module can accurately and reliably synchronize its internal clock using PTPv2 synchronization (IEEE1588: 2008). This is achieved using multiple Ethernet connection through a PTPv2 capable Ethernet switch (e.g., EX23-R).
To activate PTP synchronization, the time settings of all modules need to be changed to PTP (via MX Assistant or catman).
The master clock in a network is selected automatically according to a master clock algorithm. This allows as well the use of an external grandmaster clock as it will automatically be selected as master. When no grandmaster clock is available a module will be selected as master.
To avoid destroying the synchronization quality in heavy loaded networks, it is recommended that special PTP switches be used. The switches should support transparent clock with either E2E (end-to-end) or P2P (peer-to-peer) to compensate for the delay in the network. The transport protocol can be IPv4 or IPv6.
Each SomatXR module can synchronize its internal clock with an external NTP server. To activate NTP synchronization, the time settings of one or more modules need to be changed to NTP (via MX Assistant or catman). The NTP time is distributed to the other modules using multiple Ethernet connection through an Ethernet switch or via FireWire. Modules located close together should be synchronized via FireWire if available.
It is possible to achieve accuracies of 1 ms or higher depending on the utilization of the network and whether a dedicated NTP master is being used.
An NTP software package is included in the HBM software catman®EASY to run an NTP master on the PC.
When using only SomatXR or QuantumX MX modules in close proximity (less than 5 m), it is recommended to use FireWire connections for synchronization. All the modules are synchronized automatically when they are connected via the FireWire cable as the standard synchronization setting is "Auto", which means FireWire. For more information on FireWire connections, see Connecting multiple modules to host PC.
In a standard configuration, the module with the highest serial number takes over the master function. If a CX27 module or external synchronization source is present in the system, it automatically becomes the synchronization master. When starting the system, the system time is set once to the actual time.
If SomatXR and QuantumX MX modules alone are being used, internal synchronization is sufficient. However, if synchronous measurements are to be performed by different measurement systems, an external NTP or PTP master must be used for synchronization. This is also a requirement if the MX modules are a long distance away from one another and a FireWire connection would be too complex.
If an external synchronization source is set, the module with the best synchronization quality automatically becomes the master and synchronizes all modules connected via FireWire .
To time-synchronize the SomatXR system, the digital or analog modulated time signal is sent externally to any analog voltage input of the MX840B(-R).
The B127 format uses analog modulation. Connection is identical to that of a "10 V voltage" input.
The other formats are BCD-coded and must be connected analogous to the input "Frequency, single-pole, without directional signal".
The amplifiers can record IRIG-B signals of type B000 to B007 and B120 to B127. All modules connected via FireWire are also automatically synchronized. The coding includes the time, year and optionally, the seconds of the day.