Method for controlling data transmissions on a single channel radio frequency network

A method for controlling data transmissions on a single channel radio frequency network which is arranged to permit data transmissions in a system for remotely monitoring and controlling portable machines, the system including a plurality of nodes comprising at least one portable machine having a microcontroller for controlling operation of the portable machine, a plurality of sensors for supplying machine operational data to the microcontroller, and a radio frequency transceiver unit which communicates with the microcontroller, and at least one host computer having a radio frequency transceiver unit;

• all nodes on the network having the same status and privileges, each being able to originate and receive communications;
• each node independently performing the same method comprising the steps
• initializing each node upon power up the initializing comprising setting a CTSFLAG to zero and setting a CTS timer and a RTS timer each to a predetermined value and initiating the CTS timer;
• detecting an appropriate message during a predetermined interval of time, the message having a unique structure, and if the appropriate message is received;
• checking the message for a request to send command, and if the send command request exists, setting the CTSFLAG to zero and starting the CTS timer, and if the send command does not exist;
• checking the message for a clear to send command, and if the clear to send command is exists, setting the CTSFLAG to a one and if the clear to send command does not exist;
• checking the message for an application command, and if the application command exists, responding to the originating node of the command;
• upon not detecting an appropriate message, continuing to scan for an appropriate message;
• determining a present need to transmit a message to a predetermined node;
• checking the value of the CTSFLAG and if it is zero, checking to see if the CTS timer has expired;
• if the CTS timer has expired, simultaneously transmitting a message having a request to send command to all nodes on the network and starting the RTS timer;
• transmitting an appropriate application message to the predetermined node on the network;
• waiting for an appropriate response from the predetermined node on the network, and if an appropriate response is not detected from said node, incrementing a loop counter and waiting a predetermined time interval to re-transmit the application message;
• after an appropriate response is detected from the predetermined node, determining if the time interval of the RTS timer has expired, and if it has expired, transmitting a clear to send message to all nodes on the network and setting the CTSFLAG to one;
• and
• if the RTS timer has not expired, transmitting additional application messages during the time interval of the RTS timer.