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Kele • RUT-G Manual 2005 • www.kele.com • USA 888-397-5353 • International 901-382-6084
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RS232/485 INTERFACE KEY
This protocol is ASCII based. Data processing between the user device and network interface key is in 8-bit (byte)
character format. Data packets start with the ‘<’ (hex 0x3c) character and end with the ‘\r’ (hex 0x0d) control charac-
ter. Each data value must be separated by a comma (refer to examples at end of this spec). The first value of all data
packets is the network interface address. For RS232, this value is fixed and will always be 0. For RS485, this value is
dip switch-selectable on the network interface key circuit board and can be 0 to 255, with 0 being disabled. The sec-
ond value of each data packet holds the packet type number. The packet type number identifies the packet so that
the user device or Gateway network interface key knows how to use the data.
Data padding is not supported. Packet sizes will vary in bytes depending on data values. Ex: a value of "5" is one digit
and takes one byte, a value of "300" is three digits and takes three bytes. The number of data items within a given
packet type will remain constant.
Ex: ",4,3,125,4,10,1235,\r" Has six data items and a byte count of 21.
",4,3,1520,3,11,0,\r" Same data packet with six data items but now 19 bytes.
The data format is 1 start bit, 8 data bits (LSB first), 1 stop bit. The network interface key is capable of baud rates of
4800, 9600, and 19,200. The baud rates for the network interface key are jumper-selectable on the network interface
key circuit board. Refer to Figures 4 and 5.
RS232 Communication
Transmitting RS232 to User Device from Frontier Network Interface Key (User Device Receiving Data)
The network interface key will control the RTS line and monitor the CTS line when transmitting data to the user de-
vice. Refer to Figure 2. The network interface key will set the RTS high when ready to transmit data to the user de-
vice. The network interface key will then monitor the CTS input for an active high condition before transmitting the full
packet.
The user device must set the CTS high within 60 milliseconds from the time the network interface key sets the RTS
high (refer to figure 3) or the network interface key times out and terminates the session, returning the RTS to a low
state. The network interface key will attempt to retransmit the data packet two additional times (three transmissions)
at 60 millisecond time intervals. If, after the third attempt the user device still does not bring the CTS high, the data
packet is discarded.
In addition, if the network interface key does not transmit within the 60 milliseconds of the user device setting the CTS
high, the user device must return the CTS to a low state. Refer to Figure 3.
COMMUNICATION FORMAT
Valid Data
Timeout Period
and/or Character
Counting.
60 MS Max
Valid Data
RTS
CTS
DATA
Figure 3