
23
DRAGHAND SIMULATION:
When the Relay Limits are not enabled, the 1250B
will simulate mechanical Draghands. The Lowest position displacement can be viewed by
pressing the DOWN key. The highest position displacement can be viewed by pressing the
UP key. The Draghands may be individually reset by holdiong the UP or DOWN keys for 5
seconds. When the display reads “
CL
”, press the SELECT/ENTER key.
3.4 Serial RS-232
The Serial RS-232 (DCE) option on the Model 1250B can be used to program the
instrument or to retrieve position data from the instrument. A Null Modem Adaptor is NOT
needed with the provided Serial Cable.
There are seven operating modes for the serial RS-232 port:
Serial Disabled This mode stops all serial communication. To select this mode, use the
OP 51, RS232, SERIAL
command to choose mode
“0”
. If you are programming the instrument
through the serial port, using the serial command mode, this “disabled” mode will not take effect
until the commands “
RUN”
then “
EXIT
” are entered. The only way to de-select this “disabled”
mode is to use the menu command
OP 51, RS232
, and select another mode.
Data Logger Mode This mode causes the 1250B to transmit the present position value on
the display (including sign) once a second. To select this mode, use the
OP 51, RS232, SERIAL
command to choose mode
“1”
. If you are programming the instrument through the serial port,
using the serial command mode, this mode will not take effect until the commands “
RUN”
then
“
EXIT
” are entered.
Polled Mode When this mode is selected, the 1250B can be interrogated at any time via
the RS-232 port for the current position. This is done by first instructing the 1250B to latch the
current position by transmitting an asterisk (*) to the unit. The position is then extracted, one
character at a time, by transmitting the digits 0 through 6. Zero causes the sign character to be
transmitted, 1 through 6 causes each position digit to be sent. The decimal point, wherever it may
be positioned, is considered to be a digit. To select this mode, use the menu command
OP 51,
RS232, SERIAL
command to choose mode
“2”
.
Sampled Mode When this mode is selected, the 1250B can be interrogated at any time via
the RS-232 port for current position by transmitting a question mark (?) to the 1250B. When the
1250B receives a question mark, it responds by latching the current position and transmitting the
value on the display in ASCII form. To select this mode, use the menu command
OP 51, RS232,
SERIAL
command to chose mode
“3”
.
Serial Command Mode This mode enables programming the instrument through the serial
port. To select this mode, use the menu command
OP 51, RS232
to choose mode
“4”
. When this
mode is selected, no other serial communication can occur. In addition, if another Serial mode is
chosen it will not be activated until the commands “
RUN”
then “
EXIT
” are given through the
serial port command line.
MODBUS Mode When this mode is selected, the 1250B will respond to MODBUS
commands via the serial port (RS-232 or RS-485). To select this mode, use the menu command
OP 51, RS232
command to choose mode
“6”
.