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06.91
3.3.5
Communication control in the Transparent Mode
Communication control as in the case of the XON/XOFF and RTS-Line procedures is not
possible in the Transparent Mode. In its functionality, the Transparent Mode resembles the
RTS driver, apart from the fact that the RTS and CTS signal lines are not used. The only
signal line available is the DSR line which is scanned depending on the configuration.
Like the RTS driver, the Transparent Mode driver has full-duplex capabilities. The user can
connect both an input device (e.g. keyboard) and an output device (e.g. screen) to the
interface.
Configuring of up to two end identifiers is also possible here. In order to avoid any loss of data,
however, the user must adhere to the relevant specifications (buffer size = 246 bytes) as no
driver can be controlled. Flow control (initiating and stopping data input) must therefore be
ensured by the user.
The following parameters of the TRANSPARENT procedure are configurable:
Transmission rate
Monitoring times
DSR evaluation
Number of end identifiers (Number)
3.4
Protocols
The message frames in a computer link with the SINUMERIK 8X0 system, both bus and point-
to-point links, consist of up to four parts (see Figure "Protocols for computer link"):
•
Start of procedure
•
Protocol header
•
Message frame data
•
Procedure termination
The differences between bus and point-to-point links differ with regard to the procedure (start,
termination), protocol header and - depending on the configuration - the message frame data.
The procedure frame is described in Sections 3.1 and 3.2 or 3.3 whereas the protocol header
is explained in this section.
The protocol header of a bus link is called AP 1 header and has a length of 22 bytes including
the message frame data length.
In a serial link, each interface can be configured with or without AS512 protocol. The AS512
header has a length of ten bytes. The message frame data length requires two bytes.
The contents of the message frame data are identical for both bus and point-to-point links if
the relevant serial interface is configured with a System 800 identification. A distinction is
made between the SINUMERIK header (identification and error number) and the SINUMERIK
useful data part on the one hand and the FMS message frames on the other hand. The
description "SINUMERIK 850/880 Message Frames, Computer Link" includes a detailed
description of SINUMERIK message frames.
If a serial interface is configured without System 800 identification, the data part of the
message frame consists of useful data only.
For a detailed description of the message frame data, please refer to Section 6, Message
frames.
© Siemens AG 1989 All Rights Reserved
SINUMERIK 840/880 (PJ)
3.3.5 Communication control in the Transparent Mode
(Speed of data transmission)
(Character delay or character monitoring time)
(Check if node is active)
6FC5 197-0AB20-0BP0
3 Interface Modules
3–27
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