Woodward 2301E-ST, Инструкция по установке и эксплуатации

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Manual 26694 2301E-ST
Woodward 103
Analog Reads
Input registers are analog values that are readable from, but not writeable to, the 2301E-ST. Turbine
speed is an example of an analog read value. The values of the input registers are stored internally to the
control as floating point numbers representing engineering units (kPa or rpm). The values that are
transmitted are integers ranging from –32767 to +32767. Since Modbus can only handle integers, values
that have a decimal point are multiplied by a constant before being sent by Modbus. For example, these
input registers may be listed as the Modbus value `x100’ or `x10’ under the description heading to denote
the value is multiplied by a scaling constant. This will allow transmission of decimal parts of a unit if this is
necessary for better resolution.
See the 2301E-ST Service mode for defaulted communication constants and ranges. The 2301E-ST
supports Modbus function code 4, which involves reading selected input registers.
Analog Writes
Holding registers are analog values that are writeable to the 2301E-ST. These values can also be read by
a device performing an error check. An example of an analog write value would be a direct speed setpoint
as opposed to raise and lower commands. The values of the holding registers are also stored in the
control as numbers representing engineering units (kPa or rpm). The 2301E-ST supports Modbus
function codes 3, 6, and 16. These correspond to reading selected holding registers, writing to a single
holding register and writing to multiple holding registers, respectively. The following tables give the
address and description of all Boolean and analog reads and writes:
Modbus Scale Factors
Modbus has two limitations:

only integers can be sent across;

the value is limited between –32767 and +32767.
These limitations can be overcome by scaling the value before it is sent across the Modbus. The default
scale factor for the analog values is 1. The scale factor can be changed in the Control Assistant
(PORT_2.COM.AR_M_X) between 1 and 1000. These scaled parameters and their scale factor are
available through the Modbus. Values that require a decimal point must be multiplied by the scale factor
(10, 100 or 1000) prior to being sent across the Modbus. The value sent is then divided by the scale
factor in the Master. The Scale Factor adjusts all associated analog reads accordingly. The Multiplier
(sale factor) can be changed in the Control Assistant.
Shutdown Command through Modbus
Two different types of shutdown commands (emergency and controlled) can be issued through Modbus.
The Emergency Shutdown command instantly takes the speed setpoint, valve limiter and actuator current
to zero. The Controlled Shutdown function is used to stop the turbine in a controlled manner, as opposed
to an Emergency Trip. When a STOP command (controlled shutdown) is issued the Speed Setpoint is
ramped to zero at the optional rate. After the Speed Setpoint reaches zero, the valve limiter is instantly
stepped to zero.
The Emergency Shutdown and Controlled Shutdown commands do not influence operation of Trip Relay.
By setting the Shutdown Acknowledge BW to TRUE (one) momentarily, the Trip Relay output can be
forcedly returned to a normal state. But its trip condition is not canceled.
Start Command through Modbus
The start-up of a turbine is possible by the command through Modbus. The Open/Close of Contact inputs
(RUN/SHUTDOWN etc.) serve as the independent command in Modbus BW. These commands operate
in a momentary input.
Released