Saia-Burgess
Controls Ltd.
Manual PCD7.D23x│Document 26/795; Edition E7│15.04.2005
Software
Free Terminal Protocol Mode
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4.4
Free Terminal Protocol Mode
To be able to use the RS485 as half duplex interface, the PCD7.D23x have to be
used in a “Free Terminal Protocol” Mode (PCD7.D79x compatible).
In this serial command mode:
by default no responses will be sent.
●
Key responses are buffered
●
The other responses as found in the PCD7.D23x direct mode protocol are
thrown away and not sent.
After a special activation code has been received the buffered responses can be
requested using a serial poll command. The PCD7.D23x will never send something at
it’s own initiative.
Note that with this free terminal protocol direct control of PLC-controlled proc-
esses by the key assembly is not possible as (due to necessary polling) con-
siderable delays in the response may be found.
The interface is compatible with the PCD7.D790 and PCD7.D795 text terminals for
“protocol free” use. Additionally, in this “Free Terminal Protocol” Mode a limited set of
commands out of the direct mode command set is included.
Graphical use over the data / setup mode commands is not possible in this mode:
The Free Terminal Protocol Mode is a text only mode, the graphical access is not
supported.
In the Free Terminal Protocol Mode normally the PCD7.D23x terminal is always ac-
tive if the terminal address is set to “0”. If the terminal address is not set to “0” it is
only active after reception of the activation command. The related commands are:
D23x Command
Free Terminal Protocol Mode
Description
Details
0x1b 0x49<y><y>0x04
<ESC>I<y><y><EOT>
Select the terminal
with address <y><y>.
yy BCD ASCII coded
‘01‘...‘31‘*
Select the terminal and
deselect all other connected
terminals
0x1b 0x59 0x04
<ESC>Y<EOT>
Call terminal confirm-
ation display
Shows the welcome screen
as shown with startup
with activation indication at
the bottom line.
* Example: Value 1 is coded as 0x30 0x31 (‚01‘)
The activation address of the PCD7.D23x is set in the setup menu.
If the activation address is set to ‘00’ the terminal will be always active
.
The selection / de-selection command will be ignored.
This can be used on a point-to-point configuration, or at a
multi-drop configuration
with a number of passive displays showing the same information in parallel.
An inactive terminal will ignore all other commands and only react on the select com-