Advanced System Management and Monitoring
The PXES-2590 is equipped with an intelligent monitoring microcontroller (MCU), which communicates with the system controller through SMBus (System Management Bus) and reports in real-time 5 voltage channels (+5V,+3.3V,+12V, -12V,+5V standby), 5 backplane temperature sensors (T1~T5), and 3 fan speeds. ADLINK provides a graphical monitoring tool (FTP Monitor-PXES2590_V1.7. exe) located on the accompanying CD, which only supports ADLINK embedded controllers; If using a third-party controller, you can call the function library (Chapter 4) and develop it yourself.
3.1 Monitoring tool operation interface
After startup, the interface is divided into three parts:
Connect Control: Click Start to start polling monitoring, Stop to stop; Log Chassis Status can record logs (supports overwrite/append, can set sampling period); Over Threshold Statistics displays the statistics of over limit events; Save/Load Threshold allows saving or restoring threshold configurations.
Threshold&Control: The core control area includes target temperature (Target Temp), fan mode (Auto/Full), and alarm threshold settings for various voltages, temperatures, and fan speeds.
Chassis Status: Real time display of various voltage readings, five temperature values, and three fan speeds, with clear identification of normal/abnormal status.
3.2 Intelligent Fan and Target Temperature Setting
The rear panel is equipped with a fan switch (HIGH/AUTO):
HIGH: The fan maintains a constant full speed, suitable for high load or high temperature environments;
AUTO: Dynamically adjust speed according to the temperature of the backboard.
The default fan curve is as follows: when the temperature is below 25 ° C, the fan operates at a 40% duty cycle; When the maximum temperature exceeds 25 ° C, the duty cycle increases linearly; When reaching the target temperature (default 50 ° C), the fan is at full speed (100%). Users can modify the target temperature value (allowed range 25 ° C~70 ° C) in the software, and click Set to take effect immediately. For example, if a high-power module is installed inside the chassis, the target temperature can be set to 45 ° C to advance the fan to full speed and increase the heat dissipation margin.
3.3 Automatic selection of 10 MHz reference clock source
The PXES-2590 backplane supports three 10 MHz reference clock sources, which automatically switch according to priority:
The highest priority: PXI_CLK10-IN signal provided by the system timing slot (Slot 5);
Next highest: External 10 MHz clock at the rear BNC input port;
Minimum: Built in oscillator on the backplane (accuracy ± 50 ppm).
There are three LED indicator lights on the backplane (located on the left side of the system slot):
LED1 (VCXO present): Always on, indicating that the built-in VCXO is working properly;
LED2 (external clock present): lit up indicates detection of an external clock (from BNC or timing slot);
LED3 (phase lock complete): When lit, it indicates that the PLL has locked the external clock, and the backplane will synchronously distribute the external clock to all peripheral slots.
This feature allows users to introduce high-precision external atomic clocks or GPS tamed clocks into the system, achieving multi chassis or cross device synchronization, suitable for harsh applications such as radar arrays and multi-channel data acquisition.

SMBus programming interface and custom monitoring development
For users who need to integrate monitoring functions into their own software platform, PXES-2590 provides a complete SMBus command set (Chapter 4), allowing direct reading and writing of MCU registers through the system controller's SMBus. The following is a summary of commonly used commands (slave address 0x32, write address 0xC6):
Command code function access
0x02 Read alarm status (bit mapping: voltage/temperature/fan/rail over limit) R
0x04~0x0C reads+5V,+3.3V,+12V, -12V,+5Vsb voltage (LSB=1mV) R
0x10-0x18 reads temperature 1-5 (LSB=0.1 ° C, 16 bit complement) R
0x20~0x24 Read fan speeds 1-3 (LSB=1 RPM) R
0x26 Read MCU firmware version (high byte major version, low byte minor version) R
Read the current target temperature (range 25~70 ° C) R at 0x30
0x44 reads fan mode (0=Auto, 1=Full, 2=Low) R
0x46/0x47 block reads all status data structures (including all voltage, temperature, fan, threshold, checksum) BR
0xB0 writes target temperature W
0xB2~0xBA Write various voltage alarm thresholds (low byte is undervoltage percentage x 10, high byte is overvoltage percentage x 10) W
0xBC writes fan speed alarm threshold (LSB=1 RPM) W
0xBE writes temperature alarm threshold (LSB=1 ° C, range 0~110) W
0xC0 Restore all default thresholds (target temperature 50 ° C, voltage ± 5%, fan 800 RPM, temperature 70 ° C) W
0xC2 Reset MCU W
0xC4 Set Fan Mode W
Developers can customize monitoring by sending/receiving bytes through SMBus. For example, reading a+5V voltage: sending a write bit from address 0xC6+, command 0x04, and then receiving two bytes (with the lower byte first) to form a 16 bit signed number in mV. Block read commands 0x46 and 0x47 can retrieve all parameters at once, improving polling efficiency. The structure also contains a 16 bit checksum (0xBABA minus the sum of the first 24 words), which can be used to verify data integrity.