Instructions

UM-0085-B09 DT80 Range User Manual Page 195
RG
Host RS-232 Port
Not applicable to DT82EM/ 80LM/ 85LM
The DT80 has a 9-pin male connector for RS 232 serial communication to a computer or modem. The port is configured
as a DTE (Data Terminal Equipment) device, and the pinout is the same as that used on a PC. See RS-232 (P392) for
more details.
Configuring the Host RS-232 Port
There are three parameters that need to be set for any RS232 port, and the DT80's port is no exception:
• baud rate (data transfer rate in bits per second) DT80 default is 57600.
• serial framing format (number of data bits, parity type, number of stop bits) DT80 default is "N,8,1" – no parity, 8
data bits, 1 stop bit.
• flow control (mechanism for one computer to tell the other to stop sending) DT80 default is software flow control
(special characters are used to signal "stop" and "go").
It is essential that both ends of an RS232 link be configured identically – same baud rate, framing and flow control.
A fourth parameter that needs to be set for the DT80 host port is the port function, which specifies the protocol used by
the port – command, PPP, Modbus or generic serial.
PROFILE Settings
To view the current host port settings use the following command:
PROFILE HOST_PORT
[HOST_PORT]
BPS = 57600
DATA_BITS = 8
STOP_BITS = 1
PARITY = NONE
*FLOW = HARDWARE
FUNCTION = COMMAND
which lists the current baud rate, framing format, flow control and port function. An asterisk indicates a non-default
setting. See Profile Settings (P264)) for more details.
If required, these settings can be changed using individual
PROFILE commands, i.e.:
PROFILE HOST_PORT key=value
The following keys are defined:
Key
Value
Default
BPS
baud rate. Use
300
,
600
,
1200
,
2400
,
4800
,
9600
,
19200
,
38400
,
57600
, or
115200
.
57600
DATA_BITS
can be 7 or 8
8
STOP_BITS
can be
1
or
2
1
PARITY
can be N (none), O (odd) or E (even)
N
FLOW
NONE (no flow control)
SOFTWARE (XON/XOFF)
HARDWARE (RTS/CTS)
SOFTWARE
FUNCTION
port function (see below)
COMMAND
For example, the following commands would configure the host port for serial connection to a Modbus client (e.g. a
SCADA system), using the "standard" Modbus settings (19200 baud, 8 data bits, 1 stop bit, even parity, no flow control):
PROFILE HOST_PORT BPS=19200
PROFILE HOST_PORT PARITY=EVEN
PROFILE HOST_PORT FLOW=NONE
PROFILE HOST_PORT FUNCTION=MODBUS
Note1: These settings, as with all profile settings, will temporarily revert to default settings in the event of a "triple push" reset, see Safe
Mode
(P274)).
Note2: Do not use software flow control (SWFC) if the port is using a binary (non-ASCII) protocol, such as Modbus or PPP or some
serial sensor protocols. This is because flow control characters (XON/ XOFF) may legitimately appear in binary data, and if they do then
they will be stripped out. This will cause data errors.