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10.2.1 Data structure
10.2.2 Fieldbus parameters
Trigger byte: See "The trigger byte", Chapter 9.13‚ on page 24
Length byte: See "The length byte", Chapter 9.14‚ on page 25
10.2.3 RS-232 parameter table
10.2.3.1 Start character (232 Start character)
If this character is defined, the gateway evaluates only the data at the RS-232 interface following this start character. Each trans-
mission from the gateway via the RS-232 interface is initiated with the start character in this case.
10.2.3.2 Length 232 (232 Length)
If this byte is activated, the gateway, at the receive end, awaits as many bytes of useful data as specified in this byte by the RS-232
transmitter. At the transmission end, the gateway then sets this byte to the number of useful data items transmitted by it. If byte
"Length232" is not defined, the gateway, on reception at the RS-232 interface, waits for the end criterion if this is defined. If no
end criterion is defined either, as many characters as can be transferred in the fieldbus transmit buffer are read in via the RS-232
interface.
As a special case for this parameter also a length byte with additional Timeout monitoring can be set in WINGATE. In that case the
received characters will be discarded at a Timeout.
Attention:
If "Timeout“ is selected as end character, then this byte has no significance.
10.2.3.3 Data Area
In this data area the user data will be transferred.
10.2.3.4 End character (232 End character)
If this character is defined, the gateway receives data from the RS-232 interface up to this character. The "Timeout" criterion can
be defined as a special case. In this case, the gateway continues to receive characters until a defined pause occurs. In the special
case "Timeout" the "Length 232-byte" has no significance. At the transmit end, the gateway inserts the end character, if defined,
as the last character of a transmission.
10.2.4 Communication sequence
The useful data (data area) arriving via the fieldbus is copied in accordance with chapter 10.2.1 transparently into the RS-232
data field and transferred via the RS interface, whereby the protocol is supplemented in accordance with the configuration (start
character, end character…). NO acknowledgement is issued !
If the "Trigger byte“ (see chapter 10.5) is active, data is sent only on a change of this byte. If the "Length byte" (see chapter 10.6)
is active, only as many of the following bytes as specified there are transferred.
Trigger
(optional)
LengthBus
(optional)
Start signal
(optional)
Length232
(optional)
End signal
(optional)
Data field
Fieldbus
Data structure Universal 232 protocoll
Data field
RS
