GE VMIVME-3125 Analog Input Board

Built in power converter and ADC power supply: The power supply for the analog circuit is provided by an onboard DC-DC converter, which converts the+5 VDC of VMEbus to a regulated ± 15 VDC. The+5 VDC logic power supply for the ADC is provided by an onboard regulator, and a separate+5 V DC-DC converter is used to provide isolated analog ground for the ADC.

Configuration and Installation

Unpacking procedure: Components may be sensitive to electrostatic discharge. When handling, the board should be placed on conductive material. After unpacking, check for any transportation damage. If there is any damage, file a claim with the carrier and report to GE.

Physical installation: Power off installation, insert the board into the appropriate slot of the chassis, ensure correct alignment and orientation, smoothly slide towards the mating connector until firmly seated.

Jumper installation

Board address: occupies a short I/O address space of 128 consecutive bytes, with the base address controlled by jumper E6 to E14. The installed jumper corresponds to binary 0, and the uninstalled one corresponds to binary 1. The factory default address is short I/O $0000 (all jumper installations).

Address modifier: Jumper E16 determines the access mode of the response, including monitoring, non privileged, or both.

Input configuration: Three jumpers (J4, J5, and E5) are used to configure single ended or differential inputs, two jumpers (E1 and E2) control the input voltage range, two jumpers (E3 and E4) control the gain, and there are filter related jumpers. The factory default configuration is single ended, ± 10 V range, and unity gain.

Analog input connector description: 16 differential or 32 single ended analog input connections are made through the front panel 37 pin D-type connector P3, with corresponding pins and signal allocation.

Calibration Procedure: To obtain the specified accuracy of analog measurements, calibration is required for the required range and input topology. Firstly, instrument amplifier offset and BIT voltage calibration are performed, and then the corresponding offset and gain calibration procedures for the input topology are selected. Calibration requires a 5-digit digital voltmeter (DVM) and precision voltage reference equipment.

Programming

Memory mapping: occupying 128 bytes of address space, including four information and control registers, as well as a conversion data register. Depending on the jumper configuration of the board (single ended or differential input, normal or maximum buffer for differential input), there are different memory mapping tables.

Register description

Board ID register: 8-bit read-only register, offset $00, value $37, used to uniquely identify the board.

Configuration register: 8-bit read-only register, offset $01, indicating the current configuration, including input mode and filter bandwidth information.

Control/Status Register: 8-bit read/write register with an offset of $02, allowing software to control the board and indicate its current status, including functions such as stopping automatic scanning, maximum buffer, complement, mode bit, LED off, etc.

Channel pointer register: an 8-bit read-only register with an offset of $03, typically storing the input channel number currently being sampled and converted. Under specific configurations, it can determine the most recently updated data register.

Data registers: Depending on the state of the maximum buffer location, there are 16 or 32 data registers. Starting from an offset of $40, each 12 bit conversion data containing its related channel is aligned to the right within the 16 bit data register.

Built in testing function: It can test the function by applying various internal reference voltages to channel 0 input. The host software can read the value of channel 0 and compare it with the expected value. There are corresponding BIT value tables for different ranges and gain settings.

Range and gain determination: The analog gain and range can be set by the user, but the software cannot directly read these settings. It is not recommended to determine the current settings through BIT voltage stimulation, as the board must be calibrated to a single gain and range setting.

Accessing data in byte form: Data registers should typically be accessed using a single 16 bit word transfer, or two consecutive byte transfers, but there is a risk of confusion caused by data updates, which can be avoided by pausing automatic scanning or ensuring that byte accesses are continuous and undisturbed.

Current input options: VMIVME-3125-200 and VMIVME-3125-300 offer different terminal resistances, and the ADC input voltage is related to the current range, allowing for the calculation of the current signal through a formula.