GE VMIVME-2540 24 channel intelligent counter/controller

GE VMIVME-2540 24 channel intelligent counter/controller

Core functions and features

（1） Multi dimensional measurement function

Event counting: Supports input frequencies up to 2.5MHz, with a counting range of up to 232 (approximately 4 billion events) in long mode and 216 in word mode, allowing for accurate counting of external event occurrences.

Frequency measurement: The measurement range covers 0.0076Hz to 2.5MHz. In 16 bit counter mode, the maximum accuracy in the 0.007-76Hz frequency band is 0.015%. The error calculation formula for the 76Hz-2.5MHz frequency band is "100 × (frequency/5MHz)"; Supports 16 bit enhanced resolution mode (requires 2 16 bit counters), with a measurement range extended to 0.001Hz-1.25MHz, and has a 16 bit pre division function of ÷ 2-65536 (maximum clock rate of 2.5MHz).

Cycle/pulse width measurement: In 16 bit counter mode, the cycle measurement range is 400ns-131.07s, with a maximum accuracy of 0.015% for 131s-13.1ms. The error calculation formula for 13.1s-200ns is "100 × (200ns/cycle)"; 16 bit enhanced resolution mode (requires 2 16 bit counters) with a periodic measurement range of 800ns-858.9s; In 32-bit integer operations, pulse width measurement requires 2 16 bit counters, cycle measurement requires 3 16 bit counters, and supports discrete or continuous measurement modes with low data transmission delay.

Orthogonal position measurement: Supports sin/cos signal input (frequency 0-1MHz), uses a 32-bit counter, has limit/modulus check function, measurement accuracy of ± 1/4 wave (5MHz sampling rate), requires 2 channels corresponding to 1 encoder, can accurately obtain rotational or linear position information.

（2） Flexible generation function

Square wave/pulse sequence generation: pulse repetition frequency of 0.0038Hz-2.5MHz, period range of 400ns-262.1s, pulse width range of 200ns-131s; In terms of non square wave pulse width accuracy, the maximum error calculation formula for the 131s-13.1ms frequency band is 0.015%, and the error calculation formula for the 13.1ms-200ns frequency band is "100 × (200ns/pulse width)", which supports N pulse sequence outputs with programmable duty cycles.

Timer/Periodic VMEbus Interrupt: Interrupt repetition frequency of 0.0076-1000Hz, capable of asserting any 2 interrupt levels in IRQ1-IRQ7, providing an 8-bit interrupt vector, automatically clearing pending requests after interrupt triggering, facilitating system timing control and event response.

Orthogonal position control output: Control resolution up to ± 1/4 wave, maximum step rate of 1.25MHz, maximum single instruction step count of ± 32767, can drive the actuator to achieve precise position adjustment.

（3） Hardware and interface advantages

Core processor and storage: Equipped with a 15MHz 68HC000 CPU, 64KB EPROM (firmware storage) and 128KB zero wait static RAM (for data buffering and command queues), it can autonomously complete measurement and control tasks, reducing the burden on the host CPU.

VMEbus compatibility: Complies with ANSI/IEEE 1014-1987 and IEC 821-297 standards, supports A32/A24 address space, D32/D16/D8 (EO) data access, and provides a 64KB VMEbus memory window; Support privileged/non privileged address modifiers, shared RAM requires host and onboard CPU to arbitrate access, and supports non aligned data transfer.

Signal interface: Adopting RS-422 differential interface, compatible with single ended TTL input (achieved by connecting the RS-422 inverting input terminal to a 1.4V reference); Provide 24 clock channels, 24 gate control channels, and 24 discrete outputs, with a total of 24 control/measurement interfaces. The front-end panel is connected to the signal through high-density connectors (such as 96 pin discrete wiring connectors). Differential signals are recommended to use 24AWG twisted pair cables (maximum transmission distance of 4000 feet), and TTL signals are recommended to use 30AWG ribbon cables (maximum transmission distance of 50 feet).

Self checking and data exchange: Supports continuous measurement mode, allowing for repeated data collection without the need for host intervention; The data exchange complies with the ANSI/IEEE 754-1985 32-bit floating-point arithmetic standard, and the integer mode supports signed and unsigned operations with complement codes. The onboard state monitoring circuit can provide feedback on the hardware operating status.

Key technical parameters

Parameter category specific specifications

System time base 5MHz, accuracy/stability ± 0.005%

Power requirement+5V DC (allowing ± 5%/-2.5% fluctuation), typical current 4.25A, maximum current 5A

Input buffer common mode voltage limit ± 25V, differential mode voltage limit ± 5V (due to 120 Ω/1/4W terminal resistance); RS-422 differential mode

V IH (positive terminal is 100mV higher than negative terminal), V IL (positive terminal is 100mV lower than negative terminal); Single ended mode V IH=V TTL+100mV, V IL=V TTL − 100mV; Input hysteresis of 50mV, minimum rise time of 5ns, typical propagation delay of 25ns, maximum rise time of 1ms

The output buffer adopts AM26LS31 driver, with a typical short-circuit current of -60mA and a minimum differential mode output voltage of 2V