Digital Gauges: Frequently Asked Questions
Question number FAQ-0046
BCD OUT: Connection to a sequencer
This shows the recommended interface for connecting the BCD out to external devices. You can choose between positive logic and negative logic. Please note this.
(1) When receiving by voltage
BCD output, polarity output, decimal point output, error output, print command output
This shows recommended circuitry for external devices and the output specifications for the DG4120.
| Output format | Open collector output |
|---|---|
| Output IC | 74LS07 |
| Withstand voltage | max 30V For improved reliability, we recommend using it at 24V or below. |
| Maximum sink current | max 32mA |
| Residual voltage | max 0.5V |
Hold input, Reset input, BUSY input
This shows recommended circuitry for external devices and the input specifications for the DG4120.
| Input Low-Level Voltage | 0～1.4V |
|---|---|
| Input High-Level Voltage | 3～5.25V |
| Input Impedance | 1kΩ or more |
(2) When connecting to a sequencer
The BCDout signal is an open collector output, so connect the sequencer to an input unit designed for open collector signals (voltage: DC 12-24V).
Please note that connecting the external power supply with reversed polarity will damage the BCD output circuit.
The DG-4120's input specifications are for voltage signals, so it is recommended to connect the sequencer to a voltage output unit (such as TTL).
When driven by open collectors or relay contacts, malfunctions may occur due to noise or other environmental factors at the site. Please implement appropriate noise countermeasures. The diagram below shows one example.
■Voltage signal input recommended
■ Noise reduction measures example
Last updated: 2000-12-08