Tech Series GPIO (General Purpose IO)

Tech Series GPIO Interfaces use the same IO connector as the RS-485, and has serial IO and General Purpose IO functions that are configurable.

An RS232 serial data cable can be connected to pins 1, 2, and 6 to configure the internal radio modem and the MIMIC mode features.  See the RV-M21 user manual for information on how to wire an RS232 DB9 connector to the GPIO connector.

You can contact Raveon to have the device pre-configured when it is purchased, so that the RS232 serial IO pins  are not required to be use.

Configuring

The radio will auto-detect the GPIO board and set all necessary parameters to enable it.  By default, the IO pins are set to digital inputs. When configuring the pins, make sure nothing is connected to them until the IO pins are all properly configured.

IOPIN XX M is the command to set the GPIO bits on the Tech Series GPIO front panel to inputs or outputs.

XX parameter are the Hexadecimal representation of the pins being configured. For example, to configure bits 0 and 1, XX should be set to 3. FYI: GPIO pin #4 is called IO2 and is designates as XX bit 1, which is XX=02.

Summary of Input and Output functions.

The General Purpose IO pins 3, 4, and 5 can be configured with built-in commands to be either digital inputs, digital outputs, analog inputs, switched DC power output, open-drain outputs.

Digital Input Specifications:

Low-level input voltage:                         Less than 0.5V

High-level input voltage:                        Greater than 2.2V

Input resistance:                                      5K-10K pull-down resistance.

Digital Output Specifications:

Low-level Output voltage:                      Less than 0.5V

High Level Output Voltage:                   3.0 – 3.3V

Output resistance:                                   250 ohms

Open Drain Output Specifications:

Low-level Output voltage, on:               0V to 0.5V drawing less than 2.1A.

Open drain off leakage resistance      500uA, 0-5V,  < 1mA 5-20V.

High Level Output Voltage, off:            0 – 20V

Output resistance, on:                             <250 milli ohms to ground

Switched DC power output: (IO2 and IO3)   IO1 does not have this capability.

Output voltage, on:                                            Same as DC input, 90%-100%.  (Most radio support 12-28 VDC)

Maximum Output Current                               2.0 amps

On state internal resistance                             100-250mOhms.

Maximum reverse input voltage when off    DC input + 150mV

Off output off leakage resistance                   5-200uA

High Level Output Voltage, off:                      Same limit as RF board within the M21 enclosure.

Output resistance, on:                                       <250 milli ohms to ground[:]

Raveon’s Application AN230(ModbusMx) document describes in detail how Raveon’s Tech Series products can handle MODBUS type messages.

Controlling the GPIO and FIO interfaces on Tech Series products

The SCADA and Telemetry features in the M8, M6, and Tech Series radio modems can be controlled using a number of mechanisms:

1. Local commands.  Issue commands using a serial port to read and manage Telemetry parameters. Use WMX feature or RPR command to remotely manage a telemetry feature.
2. Over the Air commands. Commands to set or read I/O Telemetry parameters can be sent over the air using WMX built commands or manually in the command mode with the RPR command from a remote radio modem.
3. Modbus.  Digital I/Os may be managed using MODBUS type commands.  This document describes how to do this. MODBUS is a registered trademark of MODICON, Inc. This industry standard protocol has many user applications from many companies to control devices that process Modbus messages like Raveon’s radio modems do.
4. MIMIC. Two radio modems can be setup to MIMIC each-others IO pins. In the MIMIC mode, the state of one device’s input pin is automatically transferred to the other device’s output pin.  It does that at configurable intervals, and with default settings. MIMIC communications is great for sending switch status to remote devices.
5. Auto Report. IO status and registers can be automatically reported at configurable report rates and preset thresholds.

These SCADA features within Raveon’s wireless modems have many features and advantages:

1. Security. Over-the-air data communication can be encrypted with AES. Each radio modem can have encryption enabled, so no 3^rd party can access the wireless system.
2. Radio IDs. All Raveon data radio modems have a 16 bit ID code in them and address mask.  IDs can be used to ensure which radio talks to which radio, or to setup radios in groups. A listen address is also included in each radio so broadcasts to specific groups is easy.
3. Repeater. All Raveon data radio modems have a store-forward option, that can be configured by ID and groups of IDs so a radio modem can be used to store and forward messages.
4. GPS location. All Raveon data radio modems have a GPS option for location and can be configured to periodically report their location and status.
5. TDMA. All Raveon data radio modems have a GPS option for location and TDMA timing.  If fast updates are needed, TDMA slot timing is very efficient and ensure no RF interference.

Watchdog. All Raveon product incorporate a hardware watchdog timer, to fully reset the product in case some electrical or firmware problem exists. The makes remote systems very reliable.