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Video Text Overlay Unit with PC keyboard interface,

Real Time Clock & On Screen Counter

The RTCKBD-E unit described below has been replaced by RTCKBDBOX.

flexible keyboard
A keyboard is not included. Order the FLEXKYBD item for use with these units.


For applications that do not require a counter interface consider the RTCKBD-S unit.

The RTCKBD units allow a PC keyboard to be used to create text overlays to annotate a video picture. They are designed for general purpose video inspection tasks. For full details of the unit's operation please see the documentation.

document Documentation

The RTCKBD-E unit is housed in an ABS plastic enclosure with phono connectors for video in / out and a 2.1mm DC power socket. It is designed to be powered from the same power supply as the camera and so the unit does not have a power switch. Keyboard connection is via a 6-pin mini DIN socket for a PS/2 keyboard. These units will not work with USB only keyboards which require PC operating system support. They will only work with standard PS/2 keyboards and USB keyboards which implement PS/2 functionality. The latter can be connected via a USB to PS/2 adapter. Flexible keyboards similar to the one shown above, not included, are compatible if they have PS/2 functionality. The character size cannot be changed by the user, although some customisation of the character set is possible. Please contact us before you make your order for details of customisation.
To use the RTCKBD you will need to make connections for the keyboard, video in, video out and power as described on the RTCKBD overlay board connections page.

The unit has eight pages of text which can be edited seperately

The clock and counter display can be placed either at the top or bottom of the screen.

The RTCKBD-E unit has a 3.5mm jack socket for connecting an external rotary encoder or other circuit to provide the input to the on screen count. A 3.5mm jack plug is supplied with the unit. The counter display increments / decrements by 1 between +9999 and -9999. Please note that the counter is not a direct distance measurement. You will need to know the counts per turn and turns per distance measurement given by the encoder used to read the display. A prescale constant between 1 and 2048 can be set to allow the counter display to be adjusted to match the external count source. The position of the decimal point in the count display can be changed to one of four positions.
The encoder count is basically displayed as a number without units for flexibility in different applications. It could represent depth / distance in metres or feet for example as required. There is the facility to set up a pre-scaler for the count using the keyboard. Essentially if you had a 500 count per turn encoder you would set the pre-scaler to 500 and each turn would advance the count displayed by 1. This would count the number of turns. If you had 3 turns per metre then you could set the pre-scaler to 1500 and each count increment on screen would represent 1 metre. Set the pre-scaler to 150 and each count would represent 10cm, and so on. The decimal point can be placed to reflect the counts per whole number.

The counter can be hidden if not required. The position of the decimal point in the counter display can be changed to one of four positions to allow the count to represent fractional distances.

The counter can be reset either from the keyboard or from the reset button on the unit. The counter value is preserved when power is removed from the unit.

The direction pin is pulled high internally to give a positive count by default if left unconnected. When used with a incremental rotary encoder connect channel A to counter and channel B to direction as shown below. For details please see the
RTCKBD overlay board connections page.

Counter Pin 0 - 5V TTL, count on the rising edge
Direction Pin 5V TTL logic high for + count, 0V TTL logic low for - count
Ground Common Ground
Eight separate text pages 26 x14 characters PAL, 26 x 11 rows NTSC. Font and character size fixed.
24 hour format Real Time Clock
UK English or US International keyboard mapping available.
Compatible with colour and mono composite video signals. 1Vp-p. PAL or NTSC
RTCKBD-E dimensions 110 x 65 x 28mm LxWxH
RTCKBD dimensions 60 x 54 x 20mm LxWxH
Power supply required 9 - 12V DC
Power consumption 50mA (without keyboard)
Operating Temp. 0° - 85°C




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