Single Bit Input Port

The single input bit has been implemented for use with devices such as bar-code wands, voltage free switch contacts, etc. It is provided via the 4 pin LEMO socket pin 2. Note should made be that it is shared with the TXCLK on the V24 interface (pin5). It should not, therefore, be used at the same time as the communications when hardware handshaking is in use.

Circuit Implementation

The input is configured as a protected, pulled up CMOS compatible line:

Circuit Layout

It has a logic 1 threshold of > 3.5V and a logic 0 < 1.5V. It is protected to ±25V.

The pull-up resistor enables the use of a switch to ground to provide the input.

No debounce circuitry is provided. If it is required then software must be written for this purpose.

This is bit 3 on I/O port 2. See Port Allocations.

Pin-Out of LEMO Connector

LEMO Connector

Pin No





TX CLK or input




5V output (Wand option only)

LEMO Connector

The four pin LEMO plug is installed by aligning the red mark on the plug sleeve with the corresponding red mark on HUNTER’S LEMO socket, the square pin on the plug body must also align with the key-way on the socket. The LEMO plug is then pushed firmly into HUNTER’S socket until the outer sleeve of the plug is flush with the casing of HUNTER’S LEMO socket.

Removal of LEMO Plug

To remove the LEMO plug from HUNTER it is necessary to pull back the spring loaded outer sleeve before pulling the plug out of HUNTER’S socket.