Modbus Communication; Main Control & Safety Features; Figure 8: Xcm25D Controller Functionality Overview; Figure 9: Modbus Port And Termination Jumpers - Emerson Copeland EazyCool ZX Series Application Manuallines

Condenser fan
control
Monitoring of the discharge
line temperature

Figure 8: XCM25D controller functionality overview

2.10.3 Modbus communication

The XCM25D controller can communicate via Modbus (RS-485) connection to provide all running
data. Additional commands can also be activated through Modbus connection. The Modbus map is
available on request from the Application Engineering department at Emerson.
A pre-configured X-Web Supervisor device is also available and allows easy handling and
connectivity with the XCM25D controller.

Figure 9: Modbus port and termination jumpers

NOTE: If the XCM25D controller is connected in chain the termination jumpers must be
removed.
2.10.4 Main control & safety features
Suction pressure control: Each unit is equipped with a suction pressure transmitter. The XCM25D
controls the suction pressure by evaluating the input signal of the pressure transmitter. When using
a digital unit (ZXDY), the setpoint (C16) and proportional band (C17) need to be adjusted. The suction
pressure regulation for ZXMY units has to be defined by compressor cut-in (C01) and cut-out (C02)
values. The signal of the suction pressure transmitter is also used for additional functionalities,
pumpdown and keeping the compressor running within the approved envelopes.
Condensing pressure control: Each unit is equipped with a high-pressure transmitter. The
XCM25D controls the condensing pressure by regulating the fan speed corresponding to the high-
pressure transmitter signal. The unit controller can regulate the condensing pressure in two ways.
The first approach is to keep a constant condensing temperature. This mode is utilized by the factory
settings. The pre-adjusted setpoint is 27 °C as a universal setting. If lower condensing pressure is
required set up the condenser setpoint (E39) to a lower value. The second control way is fan
modulation based on compressor envelope. This mode of setpoint control is only available if a suction
pressure input is not used. The parameter (E38) enables/disables the mode as needed. If this
function is unused, the condensing temperature setpoint will be set as a parameter (E39) value. The
compressor is allowed to run different minimum condensing temperatures based on the suction
pressure of the compressor. This is the most energy efficient way to minimize the condensing
temperature as much as possible.
AGL_Unit_ZX_A2L_E_Rev00
Digital scroll
control (ZXDY)
Electrical
protection
Liquid injection
Alarm
management
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