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M-AI-VT-001-EN Rev.C.1
The following sensors are monitored through CIM board:
The following OEM supplied and installed stepper motors are controlled through CIM board:
The following OEM supplied and installed relays are monitored through CIM board:
Sensor Monitoring
Step Motor Control
Relay Output
Idx
Name
Description
Measurement range P(kPag) T(°C)
1
P/T_eco
Economizer P/T
P: -50~1500. T: -50~150
2
P/T_sc
Sub-cooling P/T
P: -50~4500, T: -50~150
Idx
Name
Description
Remarks
Type
1
EEV_P
Control Cold plate temperature by regulating
pressure
Factory supplied and OEM
installed
Bipolar
2
Staging
Stepper output for staging valve
OEM supplied and installed
Bipolar
Idx
Name
Description
Type
1
EV
Turn on/off motor cooling solenoid valve
low signal relay
2
Run Status
Run status
low signal relay
3
Comp. Status
Compressor status
low signal relay
Table 5
Sensors Monitored by CIM
Table 6
Step Motors Controlled
Through CIM
Table 7
Relay Outputs Controlled
by CIM
Overview of the VTT Compressor
Compressor
Communication Methods
CAN Communications
RS-485
Communication
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.
The CIM board is equipped with RS-485
ModBus connection for OEM’s system controller
communication with the VTT compressor system.
CAN (Controller Area Network) bus is a high
speed, rugged industrial field-bus which allows
devices to communicate with each other. CAN is
used for communication between the CCM
and CIM.
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).
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.
