STAR TPC detector is equipped by 120 temperature sensors placed on the East and West sector mounting wheels and on the FEE and RDO cooling manifolds. Temperature monitor (Fig. 1) is intended for reading out these sensors and provide temperature information for the slow control. These sensors are grouped by location into six groups: Inner Wheel, Outer Wheel, Inner Sector RDO, Outer Sector RDO, Inner Sector FEE, Outer Sector FEE.
Fig. 1. Temperature monitor front view.
See also Top view (sensor connectors) and Inside view.
The device is based on the Atmel AT89S8252 (Fig. 2) microcontroller running at 22.1184 MHz clock frequency. It has 8Kb static RAM to keep the temperature values and all data. There is also internal 2Kb EEPROM in the CPU which is used for keeping sensor names and numbers. Analog signals from the National Semiconductors LM34 sensors go through eight 16-channel multiplexers [MPC506] and instrumentation amplifier [AD711] to 16-bit ADC [ADS7813].
Fig. 2. Temperature monitor function diagram.
All signal lines have RC filters before the multiplexers to avoid long line noise. CPU has internal watch-dog, which attends to controller program faults and resets CPU as fast as in 0.5 s in this case. Temperature monitor can be connected to PC via standard RS-232 or RS-485 port. Besides, the device is equipped by LCD indicator to display sensors temperature, control buttons, 8+6 open collector digital outputs that can be used in alarms handling procedure. There is a possibility to connect any ±10V sensors to this device. ADC is normally working in 0÷4V range, but this could be changed to 0÷10V or to ±10V range. In spite of single +5V power, multiplexers and amplifiers are powered by ±15V via DC-DC converter [DCP020515D] and can be used for the signals of ±10V range.
Thus input/output features of temperature monitor are the following:
• 128 analog inputs (16-bit, 0÷4V or 0÷10V or ±10V, optional averaging);
• 14 digital outputs (open collector, 500mA maximum current);
• 4 optional analog outputs (12-bit, 0÷2.5V).