Note:
The second return number is a 32-bit system status word (set of 8 hexadecimal
characters) which is useful for fault finding. Refer to Fault finding on page 110.
7.5 Mixed parallel and serial operation
In mixed parallel and serial operation the pump may receive commands from both serial
and parallel interfaces.
To understand how these commands control the pump, refer to Figure: Logic interface
connection - mixed parallel and serial operation. The pump will power up with ‘None in
Control’. From this state a parallel start signal or a serial start command may be received,
resulting in the pump moving to parallel control mode or serial control mode
respectively. Serial start commands will only be received if the serial enable line is active.
The state of the serial enable line may be switched between active and inactive whilst in
mixed parallel and serial operation. The primary function of the serial enable line is to
enable the serial link. It has no direct effect on the control mode. The pump will receive
and respond to serial commands whenever the serial enable line is active, and
conversely will not receive or respond to serial commands when the serial enable line is
inactive.
Availability of the parallel standby and fail signals depends on the state of the serial
enable line and the position of the RS485/CAN/RS232 switch as described in Table: Serial
enable matrix.
Table 21 Serial enable matrix
Standby and fail lines are used for
RS232 data.
Standby and fail lines are used for
parallel Standby control and fail
indication.
Parallel standby control and fail
indication are disabled.
Serial communications are disabled.
Standby and fail lines are used for
RS485 data.
Standby and fail lines are in (RS485)
high impedance state.
*
Parallel standby control and fail
indication are disabled.
Serial communications are disabled.
* Pump target speed will switch between run speed and standby speed in response to
any data driven onto the RS485 bus by other devices connected to the bus. Activation of
the parallel start line not recommended with the RS485/CAN/RS232 switch in RS485
position and serial enable Inactive. Deactivation of the serial enable line is not
recommended with the pump running following a start from the parallel start line when
the RS485/CAN/RS232 switch is in the RS485 position.
In parallel control mode, the pump will not accept serial stop commands but will accept
all other serial commands. When serial enable is active, the pump will run at standby
speed if it has been commanded to do so by a serial standby command. When Serial
enable is inactive and the RS485/CAN/RS232 switch is in RS232 position, the pump will
run at standby speed when the parallel standby line is active.
In serial control mode, the state of the parallel Start line will be ignored but the serial
enable line provides an interlock function as shown in Figure: Serial and parallel control
flowchart. This interlock function only operates with serial start commands and
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