## 6 Facilities for Scientific Observation Instruments
### Data Collection and Remote Communication  
The data flows can be seen in Figure 9.  
In the power module cabin, the equipment's work data and controlling data are monitored by the (site master control) SMC through the various sensors arranged in certain places including voltage sensors, current sensors, temperature sensors, liquid level sensors, etc. The main controller PLC, as the core of SMC, obtains all kinds of real-time monitoring data through the one-way signal lines and then, classifies them, which decides whether should give an alarm to some device or switch it referring to its default value.  
In the instrument module cabin, the similar data flow still exists. Moreover, there are some other data flows that belong to the PCM. The core devices are monitored and controlled by the SMC and the PCM at the same time. The SMC and PCM have different foci of attention on these core devices. The SMC implements control on the equipment's power switch operation and the PCM gives priority to the equipment operation-state adjustment. The devices will not receive conflicting control instructions. For example, if PCM needs to power on a device, it will send a request to SMC, the SMC will first finish its own logical judgment, operate the switch, and return the answer action back then.  
Within a predetermined cycle, a packet of SMC's real-time data section will be sent from the main controller PLC to the PC104 monitor machine of PCM. These data packets and the PCM's real-time data section packets are compressed together and saved at PCM. Part of the data is regularly transferred to the (remote monitor) RMC system through the (iridium satellite communication) IMC.  
The (remote monitor) RMC can give instruments to the (site master control) SMC and the (PC monitor) PCM for remote intervention. These orders, issued by the RMC, flow through the (iridium satellite communication) IMC to the (PC monitor) PCM or are conveyed from the PCM to the SMC when necessary. The detailed view of the PCM communication with the SMC can be referred to in [26].  
The site scientific observation instruments can send data to the PCM at any time, using the redundant Ethernet. Then, these data will not be saved and directly sent to the (remote monitor center) RMC through the (iridium satellite communication) IMC. Correspondingly, the data from the (remote monitor) RMC to the site scientific observation instruments flow through the (iridium satellite communication) IMC and then, arrive at the (PC monitor) PCM, directly conveying to these site scientific observation instruments.  
The mass storage system network connects with the site scientific observation instruments through gigabit Ethernet. The data transmission between them can be processed without other computers.  
As is shown in Figure 9, all the real-time sampling data and control data will flow into the PC104 of PCM finally. They are saved in local hard disks with binary compressed ways, except the site  
Figure 9: Data generation (the dotted line) and flow (the full line).  
scientific observation instruments data, which can be stored in their local hard disks or in the mass storage network.  
The remote connection is installed, relying on the iridium satellite communication channel. Its main equipment is the iridium satellite modem, driven by the PC104 of the (PC monitor) PCM system. The iridium satellite modem exchanges information with PC104 through a serial port, and receives the control signals from PC104 through a multi-function port assembled in the iridium satellite modem at the same time. The external antenna, fixed on top of the instrument module cabin, is connected to the iridium satellite modem's main pillar through a special cold resistant cable.