Remote Control
57
11
Remote Control
11.1
RemoteControl
The 2795 TTR can be remotely controlled via the USB-to-RS-232 link. The system uses a standard USB-to-RS-232
cable (Straight through extension type) to connect to a standard 9 way RS-232 connector on a PC. For other
connector configurations, a suitable adaptor should be used. The configuration of the serial port on the TTR 2795 is
fixed at 9600 Baud, 8 bits, No parity, 1 Stop Bit.
The data is transferred between the host computer and the TTR using a command-response system. Once a
connection has been established, the TTR waits for a command to be sent from the host processor. As soon as it
receives the command, it decodes it and transmits a response back to the host processor. There is no mechanism for
the TTR to generate an output in the absence of a command from the remote host.
11.2
Transfer Protocol
Data is transferred as strings of ASCII text characters. All messages start with a ‘+’ character. Strings of characters or
single characters follow which are interpreted as directives, commands, sub-commands, or data Fields:. Fields: are
separated by a colon character ‘:’. A tilde character ‘~’ enclosed in field delimiters, indicates the end of a message.
+<field 1>:<field 2>:<field n>:~:
The separator, control and field characters are:
+
indicates the start of a message.
:
is the field separator delimiting the boundary between Fields:, except for the start of the first field of a message,
where the next character after the start character is assumed to be the first field character.
~
is the message terminator character, which must be enclosed within field delimiter characters – ‘
:~:
’
/
is a literal control character inserted into a field string before a +,:,~ or / character to indicate the following character
is not a control. This allows these characters to be embedded in a filed as part of a text string
The composition of the Fields: is not fixed, the encoding and decoding of messages depends on the particular
command being called. No assumptions are made about the encoding of the data by the operating system.
A command message must have a command in the first field, subsequent Fields: can contain sub-commands and
data. Command and sub-commands are single characters, additional characters are allowed in the field but are
ignored by the protocol and can be used to make the command strings more human readable, for example
+Q:D:~:
and
+Query:Date:~:
are equivalent.
When a command has been interpreted by the sever instrument and no data or specific response is required, the
server will send an OK acknowledgement message:
+OK:~:
When a command requires specific data or a specific response, the OK acknowledgement is sent at the start of the
specific response:
+OK:<response field 1>:<response field n>:~:
When a command cannot be interpreted or replied to, or if there was a problem processing the command an error
message with an error number is sent:
Summary of Contents for TTR 2795
Page 1: ...Operating Instructions HAEFELY TEST AG TTR 2795 Transformer Turns Ratio Meter Version 1 4 ...
Page 10: ...6 Introduction Maximum Roll Diameter Outer 50mm Inner 10mm ...
Page 22: ...18 Connection and Setup Figure 11 Connecting to three phase BCT ...
Page 101: ...Application Software APSW 2795 97 ...
Page 111: ...Miscellaneous 107 14 7 Conformity ...
