# Hardware URL: https://irs.systems/en/docs/cmm-iii/hardware The following figure shows a block diagram of CMM_III and its external connections:
Block diagram: test system with system power supply (5...24V) and data acquisition (CAN, LVDS-SPI), CMM_III with measurement control and range resistors R0 to R6, RS232 service/configuration interface, isolation barrier <150V, DUT supply and DUT
Figure 1: CMM_III HW Overview
General setup: - CMM_III needs 5…24V power supply on PWR/GND_Ext - The CMM_III Current Path is integrated in series to the DUT, whose current should be monitored. The measurement values can be read out by the following: - Digital output via a 32-bit SPI word at LVDS voltage level. - CAN (High-Speed-CAN with 250…1000 Kbit/s) - RS232 as ASCII-String via the service interface Additional features are: - The RS232 service interface may be also used to configure the module. - Permanent parameter storage of the configuration in Flash memory - Calculation of mean, min and max values. - Current path is electrically isolated from electronics supply and digital IO (up to 150V) - Detection of reverse current - Front panel LEDs for power good indication (as of hardware revision 2.0) > **Warning** > Please note, that the module is not hot-pluggable, when LVDS-SPI interface is connected! ## Connector Pinning ### System connector | Interface | Signal | Pin | Recommended wire | Remarks | | --- | --- | --- | --- | --- | | Module Power | PWR_Ext | C13 | 0,14 … 0,5mm² | | | Module Power | GND_Ext | A13, A14, A16, A17, A18, A19, A20 | 0,14 … 0,5mm² | Connect at least 1 pin | | On/Off | On/Off | A15 | 0,14 … 0,5mm² | | | CAN | CAN_L | B14 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 120 Ohm impedance | | CAN | CAN_H | C14 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 120 Ohm impedance | | LVDS-SPI | CLK_In+ | B15 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | CLK_In- | C15 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | En_In+ | B16 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | En_In- | C16 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | Rx+ | B17 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | Rx- | C17 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | Tx+ | B18 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | Tx- | C18 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | En_In+ | B19 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | En_In- | C19 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | CLK_Out+ | B20 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | LVDS-SPI | CLK_Out- | C20 | 0,14 … 0,5mm² Twisted pair | Wire with ~ 100 Ohm impedance | | Current Path | Curr_In | 4x High current pin A1-A12, B1-B12, C1-C12 | 1…4 x 10mm² | Depending on applied currents use 1 to 4 wires with appropriate diameter for both input and output, respectively. For currents above 60A use all 4 pins both for input and output. | | Current Path | Curr_Out | 4x High current pin A21-A32, B21-B32, C21-C32 | 1…4 x 10mm² | Depending on applied currents use 1 to 4 wires with appropriate diameter for both input and output, respectively. For currents above 60A use all 4 pins both for input and output. | ### RS232 service connector | Interface | Signal | Pin | Recommended wire | Remarks | | --- | --- | --- | --- | --- | | RS232 | CMM_Tx | 2 | Standard 9pol. 1:1 cable | Send data to PC | | RS232 | CMM_Rx | 3 | Standard 9pol. 1:1 cable | Receive data from PC | | RS232 | GND | 5 | Standard 9pol. 1:1 cable | GND connected to GND_Ext | Note, that the RS232 is a service connection. Normal operation uses the system connector with CAN or LVDS-SPI interface. ### Mating system connector The following components may be used for the mating connector on the test system. 1 connector with 8 high current pins is needed. Different versions for crimping or soldering from two manufacturers can be found in the following table. | Item | Quantity | Order Number | Manufacturer | Remarks | | --- | --- | --- | --- | --- | | DIN41612 Type M 24+8 | 1 | `09 03 224 6804` | Harting | | | DIN41612 Type M 24+8 | 1 | `354 116` | ERNI | | | High current pin | 8 | `09 03 000 6115` | Harting | Crimp version | | High current pin | 8 | `09 03 000 6103` | Harting | Solder version | | High current pin | 8 | `594 182` | ERNI | Crimp version | | High current pin | 8 | `594 176` | ERNI | Solder version | ## Dimensions CMM_III is designed on a 160mm x 100mm Euro card, including front cover with a width of 25,4mm (5HP) and a standard DIN41612 connector. With these dimensions it fits to standard 19” / 3HU carriers and racks.
CMM III module with front panel, dimensions 130mm (3HU) front panel height, 100mm board height, 160mm board length, 25,4mm (5HP) front panel width
Figure 2: CMM_III Dimensions
## Technical data ### Current Path Depending on the applied currents, the measurement current path must be wired with a low resistance to maintain low voltage drops. I.e., use short wires and as much high-current-pins as possible – both for current input and current output. Every High-Current pin may carry up to 40A DC maximum. But more used high current pins with wires of high diameter both yield lower voltage drops and temperature at CMM_III, because of heat conduction. Lower temperature also means lower drift. | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | DC Current | 0 | | 100 | A | operation under the following conditions: 25°C ambient temperature without airflow; 50° Ambient Temperature with airflow ~2m/s | | Worst case DC Current | | | 160 | A | 25° Ambient Temperature with airflow >6m/s on power devices and connector | | DC Current per High-current pin | | | 40 | A | 50° Ambient Temperature | | Measurement Range | | | 190 | A | Max. 3 seconds | | Single Pulse Current | | | 300 | A | Max. 100ms | | CMM_III Voltage @ OFF HW-Rev 1.2 | | | 36 | V | Module disconnects current path when PWR_Ext is below 4,8V, or ON/Off is at low level. For HW-Rev 1.1 max. Voltage is 30V! | | Leakage current @ OFF | 0 | | 20 | µA | @ 36V | | Voltage difference between GND_Ext and Current Path | -150 | | 150 | V | Limit is restricted by distance of wiring on the PCB. Electronic components are specified at least 250V | | Reverse Current detection threshold | 50 | | 1000 | mA | Depending on Temperature and components | | Reverse Current continuous | 0 | | 30 | A | | | Reverse Current single pulse | | | 200 | A | Max. 1 second. | > **NOTE: Maximum voltage, applied at the DUT** > When the CMM_III is switched off (i.e., no External power applied or On/Off-Control input is at low level) the DUT supply voltage is applied fully at CMM_III, which can handle up to 36V in OFF-state! **Thus, please make sure that CMM_III is always switched ON, when higher voltages than 36V are used for the DUT!** ### Current Sampling | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | Sample Rate (fS) | | 41,667 | | kHz | External sample rate | | Internal Sample Rate (fS_INT) | | 375 | | kHz | 9 internal samples form an external sample | | Range Changed Ignored Samples Count (Dead Time) (Configurable by command `RCISC`) | 6 | 6 | 255 | Samples | Since firmware 2.2.0. Default after boot: 6 samples (Note: The range may change (rise) during this time if the dropout voltage rises too high. This will reset the dead time timer!) | ### Module Supply Apply a power source on PWR_Ext/GND_Ext. It is recommended not to use the DUT power supply to make sure that measurement device power is separate from DUT power. Typical applications use 5V, 12V or 24V power supplies. Several other components may be supplied by the same power source. Nonetheless, because of CMM_III wide input voltage range, it is possible to use DUT-Power for powering CMM_III. Note, that current path is disconnected, when no power is applied. | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | Supply Voltage | 4,9 | | 26 | V | PWR_Ext to GND_Ext | | Supply DC Current @ 5V | 190 | 210 | 250 | mA | | | Supply DC Current @ 12V | 80 | 92 | 120 | mA | | | Supply DC Current @ 24V | 40 | 51 | 70 | mA | | | Supply Inrush Current | | 1,2 | 1,5 | A | Inrush current for approx. 5ms @ dU/dt = 1V/ms | ### DC Accuracy Accuracy of the module is verified at DC currents. Every module passes a calibration procedure at IRS. The module may be re-calibrated. | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | Accuracy uncalibrated | | 0,5 | 2 | % of Range | Max in % of respective Range | | Accuracy calibrated | | 0,2 | 1 | % of Range | Max in % of respective Range | | Resolution Range_0 | | | 100 | nA | Limited by output data step size. | | Resolution Range_1 | | | 404 | nA | | | Resolution Range_2 | | | 4,04 | µA | | | Resolution Range_3 | | | 40,3 | µA | | | Resolution Range_4 | | | 403 | µA | | | Resolution Range_5 | | | 4,03 | mA | | | Resolution Range_6 | | | 46,8 | mA | | ### DC Voltage Drop Voltage drop is the voltage between current input and output, measured on the module connector. The drop on the female power connector pins and the wiring must be added. | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | Drop @ 100µA | | 70 | 80 | mV | Range_0 | | Drop @ 1mA | | 70 | 80 | mV | Range_1 | | Drop @ 10mA | | 70 | 80 | mV | Range_2 | | Drop @ 100mA | | 70 | 80 | mV | Range_3 | | Drop @ 1A | | 90 | 100 | mV | Range_4 | | Drop @ 10A | | 100 | 120 | mV | Range_5 | | Drop @ 40A | | 45 | 60 | mV | Range_6 | | Drop @ 100A | | 120 | 150 | mV | Range_6 | | Drop @ 160A | | 200 | 230 | mV | Range_6 | ### On/Off Interface The digital input On/Off is used to switch the current path of the CMM_III on or off. The current path is **connected**, **when** a **high** level is applied. The current path is open, when a low level is applied. | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | On/Off Control – Low = OFF | -0,7 | | 1,0 | V | | | On/Off Control – High = ON | 3.0 | | 25 | V | | | On/Off Control Input Resistance | | 15 | | kOhm | 0…3,3V | | On/Off Control Input Resistance | 5 | | 15 | kOhm | 3,3…25V | > **NOTE: Maximum voltage, applied at the DUT** > When the CMM_III is switched off (i.e., no External power applied or On/Off-Control input is at low level) the DUT supply voltage is applied fully at CMM_III, which can handle up to 36V in OFF-state! Thus, please make sure that CMM_III is always switched ON, when higher voltages than 36V are used for the DUT! ### CAN Interface The integrated CAN interface is a common High-Speed CAN interface. | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | Voltage at CAN_H or CAN_L | -0,5 | | 5,5 | V | Against GND_Ext | | Input range, transient pulse CAN_H and CAN_L | -25 | | 25 | V | | | Dominant output level | 1,2 | 2 | 3 | V | | | Recessive output level | -120 | 0 | 12 | mV | | | Data rate | | | 1000 | kbit/s | | For further details, see datasheet SN65HVD230 and [CAN](/en/docs/cmm-iii/hardware#can). ### LVDS-SPI Interface | Item | Min | Typ | Max | Units | Remarks | | --- | --- | --- | --- | --- | --- | | Voltage Range | -0,2 | | 2,7 | V | LVDS-SPI inputs | | Termination | | 100 | | Ohm | LVDS-SPI inputs | | Differential input voltage range | 100 | 350 | 600 | mV | LVDS-SPI inputs | | Common mode input voltage range | 0.3 | 1.2 | 2.2 | V | LVDS-SPI inputs | | Differential output voltage range | 247 | 350 | 600 | mV | LVDS output | | Common mode output voltage range | 1.125 | 1.25 | 1.375 | V | LVDS output | | LVDS Interface Baudrate (typical no feedback) | 500 | 1250 | 1500 | kBit/s | Without Clock feedback | | LVDS Interface Baudrate (maximum with feedback) | | | 15000 | MBit/s | With Clock feedback to system | For further details, see datasheet DS90LV049 and [LVDS-SPI](/en/docs/cmm-iii/hardware#lvds-spi). ## System Integration The following section handles the hardware issues about the interfaces for accessing measurement data. For integration of the current path and the power supply, see the remarks in the [technical data](/en/docs/cmm-iii/hardware#technical-data). ### CAN The High-speed CAN interface may be used to read measurement data. Any High-Speed CAN interface from any vendor may be applied as counterpart for data acquisition. Make sure that termination of the entire bus is implemented properly with two times 120 Ohm at the respective far end of the bus. No other termination resistors are included. Wires must be twisted pair with an impedance of 120 Ohm. Every CMM on the bus should run at the same baud rate and use different CAN IDs. CAN ID and baud rate may be configured via the RS232 service interface and are stored permanently in Flash memory. For integration as a single module in a test system setup, please add a CAN counterpart with a termination resistor of 120 Ohm. CMM_III includes 120 Ohm -termination which can be enabled or disabled by a jumper switch (see figure 3). If several CMM_III are connected in parallel to one CAN interface, the termination resistor of every single CMM_III has to be disabled. A single termination must be included at the far end of the CAN bus. See the following figure for disabling of the termination resistor with the **jumper switch J3, which is marked in red**:
CMM III board with jumper J3 for CAN termination marked by a red circle, arrows Disable (left) and Enable Termination (right)
Figure 3: CAN Termination Resistor
See also [CAN Backplane](/en/docs/cmm-iii/hardware#can-backplane), when using backplane and CAN interface. ### LVDS-SPI > **Warning** > As of hardware revision 2.0, LVDS support is no longer available! On hardware revision 1.4, LVDS support is only available on request! #### Implementation Options LVDS-SPI is integrated to read data from CMM at a higher data rate, than available via CAN. **But LVDS SPI may not be used in a harsh test system environment.** For a single module, the following setup may be used. Note, that every signal in the diagram is actually a differential pair. With this setup data rates of approximately 1,5Mbit/s can be achieved. With this speed a sample rate of up to 20kS/s can be achieved for a single module.
Data acquisition connected to CMM_III: Clock to Clk_In, Enable to En_In, Data from Tx
Figure 4: LVDS-SPI for a single module at data rates up to 1,5Mbit/s
When higher data rates than 1,5Mbit/s are applied, the enable and clock line must be fed back to the data acquisition system. With this setup, Data, clock-feedback and enable-feedback may be evaluated synchronously. Otherwise, the delay through the CMM may cause corrupt data.
Data acquisition connected to CMM_III: Clock and Enable in, Data from Tx, Enable_Feedback from En_Out and Clock_Feedback from Clk_Out
Figure 5: LVDS-SPI for a single module at data rates up to 15Mbit/s
The LVDS-SPI interface is designed in a way to concatenate several CMM’s in a daisy chain type, as illustrated in the following figure.
Three CMM_III in a daisy chain: Clk_Out, En_Out and Tx of each module connected to Clk_In, En_In and Rx of the next, Data and optional Enable_Feedback and Clock_Feedback back to the data acquisition
Figure 6: LVDS-SPI “Daisy chain” for several modules
The maximum number of CMMs depends on data rate, sampling rate and performance of the data acquisition system. Typical setups are as follows: Typical setup 1: - 1…10 CMMs - sampling rate of 2,5kS/s. - clock rate of 1,25Mbit/s - feedback of clock and enable not necessary Typical setup 2: - 1…10 CMMs - Sampling rate of 20kS/s - clock rate of 10Mbit/s - Feedback of clock and enable necessary. Please note, that in any case, the wires for clock, enable, Rx and Tx must be at least properly twisted with a maximum length of approx. 1m. When higher distances must be covered, please use the backplane, described in [Backplane for easy connection](/en/docs/cmm-iii/hardware#backplane-for-easy-connection), including shielded CAT5…CAT7 cables. In harsh environments, always use the backplane. > **Warning** > Please note, that the module is not hot-pluggable, when LVDS-SPI interface is connected! #### Data Acquisition with IRS MesSy The standard device for data acquisition is the IRS MesSy. MesSy is a generic re-usable multifunction measurement device, especially designed for lifetime test of automotive control units. All software components are integrated ready to use a single CMM or several CMMs in daisy-chain. Evaluation of minimum, maximum and average is included. Streaming of CMM data is available. For further information see [https://www.irs.systems/id/irs-messy/](https://www.irs.systems/id/irs-messy/) [https://www.irs.systems/de/id/irs-messy/](https://www.irs.systems/de/id/irs-messy/) (German) The following table shows the connections of MesSy and CMM: | MesSy signal | MesSy Pin @ X1 | CMM_II Signal | CMM_III Pin | wire | Remarks | | --- | --- | --- | --- | --- | --- | | LVDS_Out_3+ | B16 | Rx+ | B17 | Twisted pair | First CMM in chain | | LVDS_Out_3- | C16 | Rx- | C17 | Twisted pair | First CMM in chain | | LVDS_Out_2+ | B15 | En_In+ | B16 | Twisted pair | First CMM in chain | | LVDS_Out_2- | C15 | En_In- | C16 | Twisted pair | First CMM in chain | | LVDS_Out_1+ | B14 | Clk_In+ | B15 | Twisted pair | First CMM in chain | | LVDS_Out_1- | C14 | Clk_In- | C15 | Twisted pair | First CMM in chain | | LVDS_In_1+ | C12 | Tx+ | B18 | Twisted pair | Tx from the CMM, which is the last in chain | | LVDS_In_1- | B12 | Tx- | C18 | Twisted pair | Tx from the CMM, which is the last in chain | | Trigger 1…16 | A7-A12, B7-B11, C7-C11 | On/Off | B15 | Single wire | Use any of the 16 Trigger lines from MesSy | Following example shows the connection of the communication lines, power and On/Off-control of two CMMs:
Wiring diagram: IRS MesSy X1 connected to CMMII_DUT1 and CMMII_DUT2 via VG_24+8 connectors, LVDS lines, power +24V/0V and On/Off control
Figure 7: MesSy connections
#### Data Acquisition with NI Compact RIO For data acquisition IRS provides interface modules for the Compact-RIO platform from National Instruments. The software may be integrated into the user’s application. For data acquisition with Compact-RIO please contact IRS. #### Custom Data Acquisition Any module with an SPI-interface may be used for data acquisition, like microcontroller devices. The level of each signal must meet the LVDS standard to maintain proper communication over long wires in harsh environments. See [LVDS-SPI data output](/en/docs/cmm-iii/functional-description#lvds-spi-data-output) for timing and data format of the communication. ### Backplane for easy connection To access the interfaces with an easy wiring, the use of the additional backplane is recommended. Especially when using LVDS-SPI, standard cables may be applied, which reduce the efforts for wiring and provide proper shielding. Three backplanes are available: - LVDS-SPI / 5HP width (25,4mm) - CAN / 5HP width (25,4mm) - LVDS+CAN / 8HP width (40,64mm) #### LVDS-SPI Backplane LVDS-SPI backplane may be used, when no CAN interface is necessary and many CMMs must be integrated on small room. The backplane enables easy connection of the LVDS-SPI interface with standard CAT5…CAT7 cables, while providing proper shielding ![LVDS-SPI backplane: photo and drawing with On/Off input, optional PE for shield, 5…24V power input, LVDS interface to test system or previous CMM (K4), jumpers to set at last CMM in the chain, LVDS interface to next CMM (K1), shield pad to connect to housing](/docs/assets/cmm-iii/images/cmm3-lvds-backplane.jpg) Following figure illustrates the options, how to pass data back to the data acquisition system. First option is used for clock rates up to 1,5Mbit/s, second option needs the clock and enable feedback for higher data rates.
Two chains of three CMM_III on backplanes connected via K4 Prev and K1 Next: first with jumper closed at the last backplane, second with jumper opened and Data and Feedback cable back to the data acquisition
Figure 8: LVDS-SPI backplane options
#### CAN Backplane CAN Backplane may be used, when no LVDS-SPI interface is necessary and many CMMs must be integrated on small room.
CAN backplane with D-Sub connector (7: CAN_H, 2: CAN_L, 5: GND), 5…24V power input and On/Off input
Figure 9: CAN backplane options
#### LVDS+CAN Backplane LVDS-SPI and CAN may be both accessed, with the drawback that more room must be reserved for the connectors.
LVDS+CAN backplane with D-Sub connector, two RJ45 connectors and power/On/Off terminal
Figure 10: LVDS-SPI + CAN backplane