Title: SPC1000 Basic Pump Controller User Manual
Page: 4of 7
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To change type of operation hold down the rotary encoder knob while powering up the timer. You will
see the display change from CYC for cycles per minute operation, then ON OFF for On time Off time
operation and bUS for Modbus control. When it displays the type of operation you desire release the
encoder knob. Then you will momentary see SEL displayed followed by the mode you selected. By
default it will go to Battery voltage display selection and begin to display the battery voltage for about
three seconds and then follows by displaying temperature.
If you select Modbus operation (bUS) as soon as it says SEL, press the Knob down and hold it until it
displays Adr and then Set, at this point release the knob and a number will be displayed. This is the
Modbus address, rotate the knob until you have the Modbus address you want. Then press and release
the knob, it will say rdY for ready. The timer is now ready to operate with the Modbus slave address you
selected. Modbus operation is RTU mode, 8 data bits, no parity, 9600 bps. Address range is settable
from 1 to 60, with a default of 20.
The first time the timer is powered up in the Modbus mode the timer will be in a halt mode. Once
Modbus has requested the unit to turn on, future power ups will operate as per the last Modbus
request.
Modbus (Remotely Control Mode, bUS Mode)
The Modbus mode requires that you connect the RS485 signal to the pluggable terminal block. A
Modbus Master will control all pump operations via communication over the RS485 connection. This
connection requires three wires, Data+, Data-, and Ground. The baud rate is 9600, Modbus Protocol
Mode - RTU Slave, 1 stop bit, No parity. Modbus Address is selectable from 1 to 60. Modbus will control
operation based on information written to the register map (See Appendix A). No termination is on the
RS485 connection-user provides the required external 120 ohm resistor if needed.
During Modbus operation the rotary knob does not have any function (other than displaying of
information) as all operation is controlled by the Modbus master. The push button switch will operate as
follows. If you press the Push button on the bottom center the display selection LEDs will change what is
being displayed.
During Modbus operation the Display will normally display bUS when running under Modbus control
and will display hLt when Modbus commands the timer to stop.
When in Modbus mode after power up in the run mode they will be 4 short pump cycles, to indicate the
timer is under Modbus control.
NOTE: In the event of a power fail (or when powering Off to On) the timer operation will be as last as
commanded by Modbus. In other words, if the timer was in the halt mode, when power comes on it will
be in the halt mode. If the timer was running when there was a power off, it would resume operation
when power returns. Also, in Modbus mode you may use the input from an external contact to halt
operation and it can be read it via a Modbus register.
If Modbus is inhibiting operation, the display will flicker when it should be blank. If the display is active
you will see hLt flash and toggle with the actual display selection reading.
