Emerson iPro, Инструкция по установке и эксплуатации

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26 • iPro Case Controller I&O Manual FM V1.01 026-1738 Rev 1
10.3.2.2. Superheat Only Mode-Control Value
Failure
In the event that a suction pressure transducer fails or suction

temperature sensor fails, the EEV will be driven to the position de-
fined by parameter SHF%.
10.3.3. Suction Control Mode
Selecting the Suction control mode can be done by setting

parameter CRE=suction . The Suction mode is designed to

perform temperature control and EEPR valve regulation for a line-
up of refrigerated cases. Case controllers in this mode are

designated as either master controllers or slave controllers, with
the master controller regulating EEPR and liquid line solenoid
valve for the refrigeration circuit lineup. The slave case

controllers communicate with the master controller through the
RS485 slave port on each device. Case temperature information
from the slave controllers is shared with the master over this

connection. The master case controller regulates the EEPR to
maintain the case temperatures to the target setpoint. The

maximum number of case controllers in a lineup is six (6), where
one of the six (6) is the master controller. The EEPR regulation
can be done based on the average, minimum or maximum case

local temperature, where local means the discharge air sensors are
connected to the master controller only. The EEPR regulation can
also be done based on the average, minimum or maximum lineup
temperature, where
lineup means all the case controllers are

connected to the RS485 slave network. The selection is made
through the parameter SSCP .
10.3.3.1. Suction Control Mode-PID
The EEPR valve regulation is accomplished by comparing control value to the target setpoint and determining a PID output value for
the position of the EEPR valve. The PID control can be put into Manual or Automatic mode by setting the P value. When the P value is
set to 0, the application will automatically adjust the proportional band value to find the best stable value for regulation.
10.3.3.2. Configuring Controllers for Suction Control Mode
To configure the controller as a master in Suction mode, the following parameters must be set:
Parameter Recommended Value
PB 0-for Automatic mode
INC 0
DER 0
Table 10-1 - Recommended Settings
Parameter Description Parameter Value for Master
Controller
CrE Control Type Suction
SSCP Superheat and suction control probe selection User choice, Average Lineup

Recommended
EEV EEV driver Not Present
EEVCnt Number of EEVs in the case 0
StandaloneCC Yes = Controller is standalone (no lineup)
No = Controller is a master or slave in a lineup NO
XEV20D-1 V1 Valve assigned to XEV20-1 valve output 1 EEPR
S1Addr Modbus address of slave device 1 2 if 1 slave CC is present; otherwise set at 0
S2Addr Modbus address of slave device 2 3 if 2 slave CC are present; otherwise set at 0
Table 10-2 - Master Controller Configurations for Suction Control Mode