Worth Data 701 RF manual Relay n Cannot be, Heard by the Base Notify Supervisor Press ANY KEY

Relay Existence setup parameter. By default, the RF Terminal is not configured to look for Relays. This setup parameter can only be accessed

via the RF Terminal keypad - it cannot be configured using the bar coded RF Terminal Setup Menu. See Chapter 2; RF System Setup for details.

Once the RF Terminal is Relay-ready, it can use the Relay instead of the Base Station to communicate. If a RF Terminal tries to transmit 10 times to a Base Station without a response, it broadcasts a “who can hear me” message. If both the Base Station and the Relay hear the message, whoever answers back to the RF Terminal first becomes the point of contact for that RF Terminal.

Once a RF Terminal has established communication with a Relay, it addresses that particular Relay until another communication failure (10 transmissions with no response) occurs. If a Base Station is within hearing distance of the RF Terminal, it will ignore messages meant for the Relay.

When a Relay receives data from a RF Terminal, it then transmits that data to the Base Station over RS-422 twisted-pair cable. The Base Station in turn transmits data (via cable) for that RF Terminal to the Relay, for subsequent broadcast to the RF Terminal.

Relays are “dumb”. Relays do not know whether a transmission was received by the Base Station or not, so it is up to the RF Terminal to retransmit its data if it does not receive a message from the Host Computer (via the Relay). The Relay can recognize data from the Terminal though and if it receives 10 re-transmissions from the RF Terminal, the Relay assumes that the Base Station cannot hear it and broadcasts the message:

RELAY n CANNOT BE

HEARD BY THE BASE

NOTIFY SUPERVISOR

PRESS ANY KEY

At this point, the RF Terminal puts out the “who can hear me” message. The RELAY n CANNOT BE HEARD message usually indicates a cabling problem and should be checked out immediately.

Sometimes a Relay gets a response from the Base Station that is partial data or garbage. The Terminal retransmits its data since it has not received a new prompt. If this occurs ten times, the RF Terminal broadcasts, “who can hear me”. At this point the Relay is still functioning and answers the RF Terminal’s call. Should the Relay respond to the RF Terminal first, the whole sequence starts again. If the Relay again gets “garbage” messages from the Base and the Terminal re-transmits 10 times, then the Relay concludes that there is something wrong and broadcasts the RELAY CANNOT BE HEARD message. This situation indicates that you may have an electrical “noise” problem – check your cabling as well as any electrical equipment that is in the area.

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