ELMBs for the RICH detectors


The ELMBs for the RICH detectors are used to collect environmental information and interface sensors to WinCC. The ELMB is a 16 bit differential ADC with 64 inputs that are multiplexed. The range full input range can be adjusted from 25 mV to 5 V and set as unipolar or bipolar. The ELMB motherboard can accommodate adaptors that allow easy interface to specific sensors: pt100 (4 wire), pt1000 (2 wire), pt10000 and NTC (2 wire).

The following sensor types are used by the RICH group:

Using the official pt100 motherboard adaptors
Directly in the ELMB input using the appropriate range (e.g. humidity sensors)
Current (4..20 mA)
These sensors are interfaced to the ELMB inputs by adding a 1 Ohm resistor on the return power line. The current creates a voltage drop in mV equal to the current in mA and this voltage in read by the ELMB operating in an appropriate range. Having the 1 Ohm resistor on the return line (negative) keeps the common mode of the differential voltage close to zero.

The ELMBs are kept in a crate in the RICH1 balcony and RICH2 bunker (one for each A and C side). They present to the outside a number of connectors. What gets connected where is described in these EDMS documents:

ELMB Power Supply Unit and Connection to WinCC

The ELMBs communicate via a CANBUS and get their power (from D2) in a single multi-wire cable.

And ELMB PSU can provide power to two CAN buses, A and B. The ELMB PSU for RICH1 is the first PSU from the left in D2C02 and for RICH2 the 2nd from the left.

The RICH2 A side ELMB box is connected to the cable 4RCCERDE007101. This cable is connected to the RICH2 ELMB PSU in port A. Cable 4RCCERDE007102 is the spare cable for the A side

The interface from the CANBUS to WinCC is a USB device (two separate USB connections) with 16 CAN ports. Ports 0--7 are connected to r1cc0401 and ports 8-15 are connected to r2cc0402:

  • r1cc0401
    • Port 0 → RICH1 ELMBs (one box)
  • r2cc0402:
    • Port 8 → A side
    • Port 9 → C side

Implementation in WinCC

The ELMB datapoints have been created using the standard ELMB tools:
The datapoints that correspond to pt100 sensors convert the voltage measurement from two channels (4 wires) into a temperature at the OPC configuration file. A non-standard conversion is implemented for the pt100 inside the radiator volume of RICH2 because the connection from the patch panel to the the sensors inside RICH2 is with two wires (avoid this mistake next time). The non-standard OPC configuration file is attached to this page.
Pressure sensors
The pressure sensors are read as voltage from the 1 Ohm resistor and converted to pressure in a separate datapoint (type AnalogDigital) using a DP Function. This allows the archiving of the raw data in case the conversion needs to be re-calibrated.
The voltage is converted to humidity in the same datapoint using a conversion formula. The raw date is not kept.

RICH2 pt100 inside the CF4 volume

There are 20 pt100s inside the CF4 volume in RICH2. They are hanging from the mirror supports. The positions of the sensors and the corresponding ELMB (63) channel are shown below. A and C are the A and C side and Mirror and Back is the mirror side of the support and the other side.
pt100 ELMB Channels
FlatA_1 00--01
FlatA_2 02--03
FlatA_3 04--05
FlatA_4 06--07
SphericalA_1 08--09
SphericalA_2 10--11
SphericalA_Mirror 12--13
SphericalA_Back 14--15
SphericalC_1 16--17
SphericalC_2 18--19
SphericalC_Mirror 20--21
SphericalC_Back 22--23
FlatC_1 24--25
FlatC_2 26--27
FlatC_3 28--29
FlatC_4 30--31
FlatA_Mirror 32--33
FlatA_Back 34--35
FlatC_Mirror 36--37
FlatC_Back 38--39

-- AntonisPapanestis - 2020-11-16

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XMLxml OPCUACANOpenServer.xml r1 manage 14.3 K 2020-11-16 - 13:56 AntonisPapanestis RICH2 OPC configuration file with special conversion for RICH2 pt100, ELMB 63 inputs 0-39
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Topic revision: r3 - 2020-11-16 - AntonisPapanestis
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