Sensor Monitoring; Step Motor Control; Relay Output; Compressor Communication Methods - Danfoss VTT Series Applications And Installation Manual

Sensor Monitoring

Table 5
Sensors Monitored by CIM

Step Motor Control

Table 6
Step Motors Controlled
Through CIM

Relay Output

Table 7
Relay Outputs Controlled
by CIM
Compressor
Communication Methods

CAN Communications

RS-485
Communication
Overview of the VTT Compressor
The following sensors are monitored through CIM board:
Idx Name
1 P/T_eco
2 P/T_sc
The following OEM supplied and installed stepper motors are controlled through CIM board:
Idx Name
Control Cold plate temperature by regulating
1 EEV_P
pressure
2 Staging Stepper output for staging valve
The following OEM supplied and installed relays are monitored through CIM board:
Idx Name
1 EV Turn on/off motor cooling solenoid valve
2 Run Status Run status
3 Comp. Status Compressor status
The compressor system central controller and the
compressor Control Module (CCM) communicate
internally with the relevant components with
two different platforms. It interfaces with the
CIM board using CAN bus communications, and
communicates with the drive module using
RS-485 ModBus transmission platform.
CAN (Controller Area Network) bus is a high
speed, rugged industrial field-bus which allows
devices to communicate with each other. CAN is
The Electronics Industry Association (EIA)
established the RS-485 standard as a guide
for developing a multi-drop, bidirectional
communications network.
RS-485 systems can be implemented using
two-wire or four-wire modes. The VTT Series
Compressors use the two-wire system with
a ground shield. With the two-wire system,
communication is half-duplex (cannot transmit
and receive at the same time).
Description
Economizer P/T
Sub-cooling P/T
Description
Description
The CIM board is equipped with RS-485
ModBus connection for OEM's system controller
communication with the VTT compressor system.
used for communication between the CCM
and CIM.
Each signal uses one twisted-pair line, two wires
twisted around themselves. This is known as
balanced data transmission or differential voltage
transmission (see Figure 21). The signal on one
wire is ideally the exact opposite of the signal
on the second wire. In other words, if one wire
is transmitting a high, the other wire will be
transmitting a low, and vice versa.
Since RS-485 is a multipoint communication
system, all devices are connected to the single
twisted-pair cable.
M-AI-VT-001-EN Rev.C.1
Measurement range P(kPag) T(°C)
P: -50~1500. T: -50~150
P: -50~4500, T: -50~150
Remarks
Factory supplied and OEM
Bipolar
installed
OEM supplied and installed Bipolar
Type
low signal relay
low signal relay
low signal relay
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Type