Remote Control

GPIO

The female DB9 connector on the back panel provides access to control functions. Pin 1 of the DB9 connector is Ground. Pins 2 through 5 on the top row are for GPIO input signals from the remote device, while Pins 6 through 9 on the bottom row are GPIO output signals to the remote device. Two of the GPIO input pins and two of the GPIO output pins are reserved for each hybrid as follows:

Figure 2 below shows an example typically used for triggering an external ring indicator using an external power supply and a common ground between the PSU and Pin 1 of the Hx's remote port.

Pin Number	Function
1 GPIO	Ground
2 GPI 1	Hybrid #1 - Hybrid ON
3 GPI 2	Hybrid #1 - Hybrid OFF
4 GPI 3	Hybrid #2 - Hybrid ON
5 GPI 4	Hybrid #2 - Hybrid OFF
6 GPO 1	Hybrid #1 - Ringing indicator
7 GPO 2	Hybrid #1 - ON/OFF status indicator
8 GPO 3	Hybrid #2 - Ringing indicator
9 GPO 4	Hybrid #2 - ON/OFF status indicator

Figure 2 - Example interface for exterenal ringing indicator

Input Characteristics

The GPIO inputs are designed to be universal.
They accept either a voltage source up to 24VDC, or a closure to ground which may be provided by switches, relays, or logic outputs.
In the latter case, either ‘totem-pole’ or open-collector will work.
The inputs are active low.
A built-in 10k Ohm pull up resistor is provided.

Output Characteristics

Open-collector to ground.
These will require a pull-up resistor to drive TTL-style logic inputs; most equipment has the pull-up built into the input.
If there is no pull-up, you’ll have to add one, connecting it from the output pin to a +5V source; an appropriate value is 2.2K Ohms.
Sink (pull-down) current must be limited to 400mA maximum per output with the total output restricted to 1 amp (250 mA each output if all four will be used).
The GPIO output pins can be used to provide status information to other devices or warning lamps.
Outputs are available to indicate “hybrid in use” and “line ringing”.