WEG CFW320 User manual

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Modbus RTU
CFW320
User’s Guide

Modbus RTU User’s Guide
Series: CFW320
Language: English
Document: 10009156417 / 00
Build 232
Publication Date: 03/2022

SUMMARY OF REVISIONS
The information below describes the reviews made in this manual.
Version Revision Description
- R00 First edition

CONTENTS
ABOUT THE MANUAL .................................................................... 5
ABBREVIATIONS AND DEFINITIONS ....................................................................... 5
NUMERICAL REPRESENTATION ............................................................................ 5
DOCUMENTS ................................................................................................... 5
1 MAIN CHARACTERISTICS ......................................................... 6
1.1 MODBUS RTU ............................................................................................ 6
2 INTERFACE DESCRIPTION ........................................................ 7
2.1 RS485 COMMUNICATION MODULE (CFW320-CRS485) ........................................... 7
2.1.1 RS485 module’s connector........................................................................... 7
2.1.2 RS485 Interface Characteristics .................................................................... 7
2.1.3 Terminating resistor.................................................................................... 8
2.1.4 Indications ............................................................................................... 8
2.1.5 Connection with the RS485 Network .............................................................. 8
2.2 USB COMMUNICATION MODULE (CFW320-CUSB) ................................................ 8
2.2.1 Indications ............................................................................................... 9
2.3 RS232 COMMUNICATION MODULE (CFW320-CRS232) ........................................... 9
2.3.1 RS232 module’s connector........................................................................... 9
2.3.2 Indications ............................................................................................... 9
2.3.3 Connection to the RS232 Network ............................... .................................. 9
3 INSTALLATION OF THE EQUIPMENT IN NETWORK...................... 10
3.1 COMMUNICATION RATE ............................ ................................................... 10
3.2 ADDRESS IN THE MODBUS RTU NETWORK ........................................................ 10
3.3 TERMINATION RESISTOR .............................................................................. 10
3.4 CABLES ................................................................................................... 10
3.5 CONNECTION IN THE NETWORK ..................................................................... 10
3.6 RECOMMENDATIONS FOR GROUNDING AND CABLE PASSAGE ............................... 11
4 PARAMETERS .......................................................................... 12
4.1 COMMANDS AND COMMUNICATION STATUS.......... ............................................ 12
4.2 MODBUS RTU ............................................................................................ 16
5 OPERATION IN THE MODBUS RTU NETWORK – SLAVE MODE ..... 20
5.1 AVAILABLE FUNCTIONS ................................................................................ 20
5.2 MEMORY MAP ........................................................................................... 20
5.2.1 Parameters.................................... ........................................................... 20
5.2.2 Memory Markers ....................................................................................... 21
5.3 COMMUNICATION ERRORS ........................................................................... 21
6 STARTUP GUIDE....................................................................... 22
6.1 INSTALLING THE ACCESSORY ........................................................................ 22
6.2 CONFIGURING THE EQUIPMENT ................................................................. .... 22
6.3 CONFIGURING THE MASTER .......................................................................... 22
6.4 COMMUNICATION STATUS ............................................................................ 22
7 QUICK REFERENCE OF ALARMS AND FAULTS ........................... 23

ABOUT THE MANUAL
This manual supplies the necessary information for the operation of the CFW320 frequency inverter using the
Modbus RTU protocol. This manual must be used together with the CFW320 user’s manual and programming
manual.
ABBREVIATIONS AND DEFINITIONS
ASCII American Standard Code for Information Interchange
CRC Cycling Redundancy Check
EIA Electronic Industries Alliance
RTU Remote Terminal Unit
TIA Telecommunications Industry Association
LSB Least Significant Bit/Byte
MSB Most Significant Bit/Byte
ro Read only
rw Read/write
cfg Configuration
NUMERICAL REPRESENTATION
Decimal numbers are represented by means of digits without suffix. Hexadecimal numbers are represented with
the letter ’h’ after the number. Binary numbers are represented with the letter ’b’ after the number.
DOCUMENTS
The Modbus protocol was developed based on the following specifications and documents:
Document Version Source
MODBUS Application Protocol Specification, December 28th 2006. V1.1b MODBUS.ORG
MODBUS Protocol Reference Guide, June 1996. Rev. J MODICON
MODBUS over Serial Line, December 20th 2006. V1.02 MODBUS.ORG
In order to obtain this documentation, consult MODBUS.ORG, which is nowadays the organization that keeps,
publishes and updates the information related to the Modbus protocol.
CFW320 | 5

MAIN CHARACTERISTICS
1 MAIN CHARACTERISTICS
Below are the main characteristics for Modbus RTU communication of the frequency inverter CFW320.
Interface galvanically insulated and with differential signal, providing more robustness against electromagnetic
interference.
It allows the device to operate as Modbus RTU slave.
Allows data communication for equipment operation and parameterization.
1.1 MODBUS RTU
Two transmission modes are defined in the Modbus protocol specification for the serial interface: ASCII and RTU.
These modes define the way the message bytes are transmitted. It is not possible to use the two transmission
modes in the same network. The CFW320 frequency inverter uses only the RTU mode for the telegram transmission.
It allows up to 247 slaves, but only one master.
It adds to the Modbus PDU an address and error-checking field. The association of these fields to the PDU is called
ADU (Application Data Unit).
Modbus RTU telegram format:
Address: used to identify the slave.
PDU: Modbus PDU.
CRC: field for checking the transmission errors.
The master initiates the communication sending a byte with the address of the slave to which the message is
destined. When sending the answer, the slave also initiates the telegram with its own address. The master can also
send a message to the address 0 (zero), which means that the message is destined to all the slaves in the network
(broadcast). In that case, no slave will answer to the master.
The last part of the telegram is the field for checking the transmission errors. The used method is the CRC-16
(Cycling Redundancy Check). This field is formed by two bytes; where first the least significant byte is transmitted
(CRC-), and then the most significant (CRC+). The CRC calculation form is described in the protocol specification.
In the RTU mode there is no specific character that indicates the beginning or the end of a telegram. The indication
of when a new message begins or when it ends is done by the absence of data transmission in the network,
for a minimum period of 3.5 times the transmission time of a data byte (11 bits). Thus, in case a telegram has
initiated after the elapsing of this minimum time, the network elements will assume that the first received character
represents the beginning of a new telegram. And in the same manner, the network elements will assume that the
telegram has reached its end when after receiving the telegram elements, this time has elapsed again.
If during the transmission of a telegram the time between the bytes is longer than this minimum time, the telegram
will be considered invalid because the frequency inverter will discard the bytes already received and will mount a
new telegram with the bytes that were being transmitted.
For communication rates higher than 19200 bit/s, the used times are the same as for that rate. The Table 1.1 on
page 6 shows us the times for different communication transmission rates:
Table 1.1: Communication rates and the time periods involved in the telegram transmission
Baud rate T11bits T3.5x
1200 bits/s 9.167 ms 32.083 ms
2400 bits/s 4.583 ms 16.042 ms
4800 bits/s 2.292 ms 8.021 ms
9600 bits/s 1.146 ms 4.010 ms
19200 bits/s 573 µs 2.005 ms
38400 bits/s 573 µs 2.005 ms
57600 bits/s 573 µs 2.005 ms
T11bits = Time for transmitting one byte of the telegram.
T3.5x= Minimum interval to indicated beginning and end of a telegram (3.5 x T11bits).
CFW320 | 6

INTERFACE DESCRIPTION
2 INTERFACE DESCRIPTION
The interfaces for serial communication RS485, RS232 or USB available for the CFW320 frequency inverter depend
on the selected communication module for the product. Following are presented information about the connection
and installation of the equipment, using different communication modules.
2.1 RS485 COMMUNICATION MODULE (CFW320-CRS485)
Figure 2.1: Module with RS485 interface
This plug-in module for the CFW320 frequency inverter has one RS485 interface. This standard RS485 interface
has two functions:
Point to Point Connection with remote keypad, via mini USB1connector.
Connection via RS485 for network operation, via terminals.
!DANGER!
The mini USB connector is not USB compatible, therefore, It cannot be connected to USB ports. This
connector only serves as the interface between the frequency inverter and Its remote keypad.
✓NOTE!
Although RS485 communication signal is available on both connectors – mini USB and control
terminal – these signals are the same (internally). For this reason, it is not possible to use RS485
interface as command source or reference source and remote keypad at the same time.
2.1.1 RS485 module’s connector
The RS485 interface connections are available via control terminal using the following pin assignment:
Table 2.1: RS485 connector pinout for the module (CFW320-CRS485)
Pin Name Function
25 RS485 – A (-) RS485 (Terminal A)
26 RS485 – B (+) RS485 (Terminal B)
27 GND 0V reference
28 Shield (PE) Cable shield
29 N.C. No Connection
2.1.2 RS485 Interface Characteristics
The interface follows the EIA/TIA-485 standard.
It allows communication baud rates from 9600 up to 76800 Kbit/s.
The interface is electrically isolated and with differential signal, which grants more robustness against
electromagnetic interference.
1For connections that require distances greater than 3 meters, use remote keypad connection via control terminal.
CFW320 | 7

INTERFACE DESCRIPTION
It allows the connection of up to 32 devices to the same segment. More devices can be connected by using
repeaters2.
A maximum bus length of 1000 meters.
2.1.3 Terminating resistor
It is necessary to enable a terminating resistor at both ends of the main bus for each segment of the RS485 network.
If the equipment located at both ends of the bus does not have termination resistors, use active terminating to enable
these resistors.
Table 2.2: Configuration of the switches to configure the RS485
Switch Setting Option
S1.1 = OFF and S1.2 = OFF RS485 Termination off
S1.1 = ON and S1.2 = ON RS485 Termination on
S1.1 = OFF and S1.2 = ON This combination is not allowed
S1.1 = ON and S1.2 = OFF
2.1.4 Indications
Details on the alarms, communications failures and communication states are made through the keypad (HMI) and
product parameters.
2.1.5 Connection with the RS485 Network
The following points must be observed for the connection of the device using the RS485 interface:
It is recommended the use of a shielded cable with a twisted pair of wires.
It is also recommended that the cable has one more wire for the connection of the reference signal (GND). In case
the cable does not have the additional wire, then the GND signal must be left disconnected.
The cable must be laid separately (and far away if possible) from the power cables.
All the network devices must be properly grounded, preferably at the same ground connection. The cable shield
must also be grounded.
Enable the termination resistors only at two points, at the extremes of the main bus, even if there are derivations
from the bus.
2.2 USB COMMUNICATION MODULE (CFW320-CUSB)
Figure 2.2: Module with USB connection
For this module, a USB interface with mini-USB conector is available. When connecting the USB interface, it will
be recognized as a USB to serial converter, and a virtual COM port will be created3. Thus communication is made
with the drive via this COM port.
2The limit of devices that can be connected on the network depends on the protocol used.
3It is necessary to install the USB driver on the CD-ROM supplied with the product. The COM port number created depends on the availability
in the operating system and, once connected, consult the hardware resources of the system to identify this port.
CFW320 | 8

INTERFACE DESCRIPTION
2.2.1 Indications
Details on the alarms, communications failures and communication states are made through the keypad (HMI) and
product parameters.
2.3 RS232 COMMUNICATION MODULE (CFW320-CRS232)
Figure 2.3: Module with RS232 connection
2.3.1 RS232 module’s connector
The connection for the RS232 interface is available via terminals using the following pin assignment:
Table 2.3: Pin assignment of the RS232 connector for the module (CFW320-CRS232)
Pin Name Function
25 N.C. No Connection
26 RX Receiver
27 TX Transmitter
28 N.C. No Connection
29 GND Reference 0 V
2.3.2 Indications
The alarm, fault and status indications of the communication are made through the HMI and parameters of the
product.
2.3.3 Connection to the RS232 Network
For the connection of the CFW320 frequency inverter using the RS232 interface, the following points must be
observed:
The frequency inverter RX and TX signals must be connected respectively to the master TX and RX, besides the
connection of the reference signal (GND).
The RS232 interface is very susceptible to interferences. Therefore, the cable used for communication must be
as short as possible – always shorter than ten meters.
The passage of the cable must be done separately (and if possible distant) from the power supply cables.
All network devices must be properly grounded, preferably to the same connection with the ground.
CFW320 | 9

INSTALLATION OF THE EQUIPMENT IN NETWORK
3 INSTALLATION OF THE EQUIPMENT IN NETWORK
For the connection of the frequency inverter CFW320 using the RS485 interface, the following points must be
observed:
3.1 COMMUNICATION RATE
The RS485 interfaces of the CFW320 frequency inverter can communicate using the rates defined on the Table 3.1
on page 10.
Table 3.1: Supported baud rates
Baud Rate
9600 bit/s
19200 bit/s
38400 bit/s
57600 bit/s
76800 bit/s
All network equipment must be programmed to use the same communication baud rate.
3.2 ADDRESS IN THE MODBUS RTU NETWORK
Each Modbus RTU network device must have an address, and may range from 1 to 247. This address must be
unique for each equipment.
3.3 TERMINATION RESISTOR
The use of termination resistors at the ends of the bus is essential to avoid line reflection, which can impair the
signal and cause communication errors. Termination resistors of 120 Ω | 0.25 W must be connected between the
signals +B and -A at the ends of the main bus.
It worth to mention that, in order to allow the disconnection of the element from the network without damaging the
bus, it is interesting to put active terminations, which are elements that only play the role of the termination. Thus,
any equipment in the network can be disconnected from the bus without damaging the termination.
3.4 CABLES
Recommended characteristics of the cable used in the installation:
It is recommended the use of a shielded cable with a twisted pair for the signals +B and -A, 24 AWG minimum.
It is also recommended that the cable has one more wire for the interconnection of the 0V reference signal.
Maximum length for connection between devices: 1000 m.
To perform the installation, it is recommended the use of shielded cables specific for use in industrial environment.
3.5 CONNECTION IN THE NETWORK
In order to interconnect the several network nodes, it is recommended to connect the equipment directly to the
main line without using derivations. During the cable installation the passage near to power cables must be avoided,
because, due to electromagnetic interference, this makes the occurrence of transmission errors possible.
CFW320 | 10

INSTALLATION OF THE EQUIPMENT IN NETWORK
Modbus RTU
Master
Termination Termination
Figure 3.1: Modbus RTU network installation example
In order to avoid problems with current circulation caused by difference of potential among ground connections, it
is necessary that all the devices be connected to the same ground point.
The maximum number of devices connected to a single segment of the network is limited to 32. Repeaters can be
used for connecting a bigger number of devices.
3.6 RECOMMENDATIONS FOR GROUNDING AND CABLE PASSAGE
The correct connection to ground reduces problems caused by interference in an industrial environment. Below
are some recommendations regarding grounding and cable passage:
It is recommended the use of equipment suitable for the industrial environment.
The cable must be laid separately (and far away if possible) from the power cables.
All the network devices must be properly grounded, preferably at the same ground connection.
Always use shielded cables, as well as connectors with metal housing.
Use fastening clamps in the main grounding point, allowing a greater contact area between the cable shield and
the grounding.
Avoid connection of the cable in multiple grounding points, especially where groundings of different potentials are
present.
CFW320 | 11

PARAMETERS
4 PARAMETERS
4.1 COMMANDS AND COMMUNICATION STATUS
See below the parameters related to the states and commands through the communication networks available for
the frequency inverter.
P680 - Logical Status
Adjustable
Range:
0 to FFFF (hexa)
Bit 0 = Reserved
Bit 1 = Run Command
Bit 2 = Fire Mode
Bit 3 to 4 = Reserved
Bit 5 = 2nd Ramp
Bit 6 = Config. Mode
Bit 7 = Alarm
Bit 8 = Running
Bit 9 = Enabled
Bit 10 = Forward
Bit 11 = JOG
Bit 12 = Remote
Bit 13 = Subvoltage
Bit 14 = Reserved
Bit 15 = Fault
Factory
Setting:
-
Properties: ro
Description:
The inverter status word is unique for all the sources and can only be accessed for reading. It indicates all the
relevant operating status and modes of the inverter. The function of each bit of P680 is described in Table 4.1 on
page 13.
CFW320 | 12

PARAMETERS
Table 4.1: P680 bits function
Bit Value/Description
Bit 0
Reserved
-
Bit 1
Run Command
0: there was no Run command
1: there was Run command
Bit 2
Fire Mode
0: fire Mode function inactive
1: fire Mode function active
Bit 3 … 4
Reserved
-
Bit 5
2nd Ramp
0: 1st acceleration and deceleration ramp by P100 and P101
1: 2nd acceleration and deceleration ramp by P102 and P103
Bit 6
Config. Mode
0: inverter operating in normal conditions
1: inverter in configuration state. It indicates a special condition in which the inverter cannot be enabled,
because it has parameterization incompatibility
Bit 7
Alarm
0: inverter is not in alarm state
1: inverter is in alarm state
Bit 8
Running
0: motor is stopped
1: inverter is running according to reference and command
Bit 9
Enabled
0: inverter is disabled
1: inverter is enabled and ready to run the motor
Bit 10
Forward
0: motor is running in the reverse direction
1: motor is running in the forward direction
Bit 11
JOG
0: JOG function inactive
1: JOG function active
Bit 12
Remote
0: inverter in Local mode
1: inverter in Remote mode
Bit 13
Subvoltage
0: no undervoltage
1: with undervoltage
Bit 14
Reserved
-
Bit 15
Fault
0: inverter is not in fault state
1: some fault registered by the inverter
P681 - 13-Bit Speed
Adjustable
Range:
0 to FFFF (hexa) Factory
Setting:
-
Properties: ro
Description:
It defines the 13-bit speed reference. The 13-bit Frequency Reference is a scale based on the motor rated speed
(P402) or on the motor rated frequency (P403). In the inverter, parameter P403 is taken as the base to determine
the frequency reference.
Thus, the 13-bit frequency value has a range of 16 bits with signal, that is, -32768 to 32767; however, the rated
frequency in P403 is equivalent to the value 8192. Therefore, the maximum value in the range 32767 is equivalent
to four times P403:
P681 = 0000h (0 decimal) →motor speed = 0
P681 = 2000h (8192 decimal) →motor speed = rated frequency
Intermediate or higher frequency values can be obtained by using this scale. E.g., for a 60Hz rated frequency motor,
if the value read is 2048 (0800h), then, to obtain the value in Hz one must calculate:
8192 => 60 Hz
2048 => Frequency
Frequency = 2048 x 60
8192
Frequency = 15 Hz
Negative values in this parameter indicate that the motor is running in the reverse direction.
CFW320 | 13

PARAMETERS
✓NOTE!
The values transmitted over the network have a scale limitation, allowing a maximum of 4 times the
rated frequency of the motor, with saturation in 32767 (or -32768).
P682 - Serial/USB Control
Adjustable
Range:
0 to FFFF (hexa)
Bit 0 = Ramp Enable
Bit 1 = General Enable
Bit 2 = Run Forward
Bit 3 = JOG Enable
Bit 4 = Remote
Bit 5 = 2nd Ramp
Bit 6 = Reserved
Bit 7 = Fault Reset
Bit 8 to 15 = Reserved
Factory
Setting:
-
Properties: ro
Description:
The inverter control word has read and write access only via network interface, but read only access is permitted
for the other sources (keypad, SoftPLC). Each bit function is described as per Table 4.2 on page 14. The value of
P682 is indicated in hexadecimal.
Table 4.2: P682 bits function
Bit Value/Description
Bit 0
Ramp Enable
0: stops the motor by deceleration ramp
1: run the motor according to the acceleration ramp until reaching the speed reference value
Bit 1
General Enable
0: disables the inverter, interrupting the power supply to the motor
1: enables the inverter, allowing the operation of the motor
Bit 2
Run Forward
0: run the motor in the opposite direction of the reference signal (reverse)
1: run the motor in the direction of the reference signal (forward)
Bit 3
JOG Enable
0: disable JOG function
1: enable JOG function
Bit 4
Remote
0: inverter goes into Local mode
1: inverter goes into Remote mode
Bit 5
2nd Ramp
0: acceleration and deceleration ramp by P100 and P101
1: acceleration and deceleration ramp by P102 and P103
Bit 6
Reserved
-
Bit 7
Fault Reset
0: no function
1: if in fault state, reset the fault
Bit 8 … 15
Reserved
-
P683 - Serial/USB Speed Ref.
Adjustable
Range:
0 to FFFF (hexa) Factory
Setting:
-
Properties: ro
Description:
It allows programming the motor speed reference via communication interfaces only. For other sources (HMI, etc.),
it behaves as a read-only parameter.
To enable the use of the reference written in this parameter, the product must be programmed to use the speed
reference via communication network. This is programming is done using parameters P221 and P222.
This word uses a 13-bit resolution with signal to represent the motor rated frequency (P403):
CFW320 | 14

PARAMETERS
P683 = 0000h (0 decimal) →speed reference = 0.
P683 = 2000h (8192 decimal) →speed reference = rated frequency (P403).
Intermediate or higher reference values can be programmed by using this scale. E.g. 60Hz rated frequency, to
obtain a speed reference of 30 Hz one must calculate:
60 Hz => 8192
30 Hz => 13 bits reference
13 bits reference = 30 x 8192
60
13 bits reference = 4096 => Value corresponding to 30 Hz in a 13 bit scale
This parameter also accepts negative values to revert the motor speed direction. The reference speed direction,
however, depends also on the control word - P682 bit 2 setting:
Bit 2 = 1 and P685 > 0: reference for forward direction
Bit 2 = 1 and P685 < 0: reference for reverse direction
Bit 2 = 0 and P685 > 0: reference for reverse direction
Bit 2 = 0 and P685 < 0: reference for forward direction
✓NOTE!
The values transmitted over the network have a scale limitation, allowing a maximum of 4 times the
rated frequency of the motor, with saturation in 32767 (or -32768).
P695 - DOx Value
Adjustable
Range:
0 to F (hexa)
Bit 0 = DO1
Bit 1 = DO2
Bit 2 = DO3
Bit 3 = DO4
Factory
Setting:
-
Properties: ro
Description:
It provides access for monitoring and controlling the inverter by using the communication interfaces. Each bit
represents the value for a digital output. The value written in this parameter is used as the digital output value,
providing that the function for the desired digital output be programmed for “P695 value”.
Table 4.3: P695 bits function
Bit Value/Description
Bit 0
DO1
0: DO1 output open.
1: DO1 output closed.
Bit 1
DO2
0: DO2 output open.
1: DO2 output closed.
Bit 2
DO3
0: DO3 output open.
1: DO3 output closed.
Bit 3
DO4
0: DO4 output open.
1: DO4 output closed.
P696 - AOx Value 1
CFW320 | 15

PARAMETERS
P697 - AOx Value 2
Adjustable
Range:
0 to FFFF (hexa) Factory
Setting:
-
Properties: ro
Description:
It provides access for monitoring and controlling the inverter by using the communication interfaces.
They allow the control of the analog outputs by means of network interfaces (Serial, CAN, etc.). These parameters
cannot be changed via HMI.
The value written in these parameters is used as the analog output value, providing that the function for the desired
analog output be programmed for “P696 / P697 value”, at the parameters P251, P254.
The value must be written in a 15-bit scale (7FFFh = 32767) to represent 100 % of the output desired value, i.e.:
P696 = 0000h (0 decimal) →analog output value = 0 %
P696 = 7FFFh (32767 decimal) →analog output value = 100 %
The showed example was for P696, but the same scale is also used for the parameters P697. For instance, to
control the analog output 1 via serial, the following programming must be done:
Choose a parameter from P696, P697 to be the value used by the analog output 1. For this example, we are
going to select P696.
Program the option “P696 value” as the function for the analog output 1 in P254.
Using the network interface, write in P696 the desired value for the analog output 1, between 0 and 100 %,
according to the parameter scale.
✓NOTE!
If the analog output is programmed for working from -10 V to 10 V, negative values for this parameter
must be used to command the output with negative voltage values, i.e., -32768 to 32767 represent
a variation from -10 V to 10 V at the analog output.
4.2 MODBUS RTU
See below the frequency inverter parameters that are directly related to the Modbus RTU communication.
P308 - Serial Address
Adjustable
Range:
1 to 247 Factory
Setting:
1
Properties: cfg
Description:
It allows programming the address used for the inverter serial communication. It is necessary that each device in
the network has an address different from all the others.
P310 - Serial Baud Rate
Adjustable
Range:
0 = 9600 bits/s
1 = 19200 bits/s
2 = 38400 bits/s
3 = 57600 bits/s
4 = 76800 bits/s
Factory
Setting:
1
Properties: cfg
Description:
CFW320 | 16

PARAMETERS
It allows programming the baud rate for the serial communication interface, in bits per second. This baud rate must
be the same for all the devices connected to the network.
Table 4.4: P310 options
Indication Description
0 = 9600 bits/s 9600 bit per second.
1 = 19200 bits/s 19200 bit per second.
2 = 38400 bits/s 38400 bit per second.
3 = 57600 bits/s 57600 bit per second.
4 = 76800 bits/s 76800 bit per second.
P311 - Serial Bytes Config.
Adjustable
Range:
0 = 8 bits, no, 1
1 = 8 bits, even,1
2 = 8 bits, odd, 1
3 = 8 bits, no, 2
4 = 8 bits, even,2
5 = 8 bits, odd, 2
Factory
Setting:
1
Properties: cfg
Description:
It allows programming the number of data bits, parity and stop bits of the serial interface bytes. This configuration
must be identical for all the devices connected to the network.
Table 4.5: P311 options
Indication Description
0 = 8 bits, no, 1 8-bit, no parity, 1 stop bit.
1 = 8 bits, even,1 8 bits, with even parity, 1 stop bit.
2 = 8 bits, odd, 1 8-bit, with odd parity, 1 stop bit.
3 = 8 bits, no, 2 8-bit, no parity, 2 stop bit.
4 = 8 bits, even,2 8-bit, with even parity, 2 stop bit.
5 = 8 bits, odd, 2 8-bit, with odd parity, 2 stop bit.
P312 - Serial Protocol
Adjustable
Range:
0 to 1 = Reserved
2 = Modbus RTU Slave
3 = BACnet
4 = Reserved
5 = ModBus RTU Master
Factory
Setting:
2
Properties: cfg
Description:
It configures serial port protocol.
Table 4.6: P312 options
Indication Description
0 ... 1 = Reserved Not available.
2 = Modbus RTU Slave Slave Modbus RTU serial protocol.
3 = BACnet Bacnet serial protocol.
4 = Reserved Not available.
5 = ModBus RTU Master Master Modbus RTU serial protocol.
CFW320 | 17

PARAMETERS
P313 - Action for Communic. Error
Adjustable
Range:
0 = Inactive
1 = Ramp Stop
2 = General Disable
3 = Go to LOC
4 = LOC Keep Enab.
5 = Cause Fault
Factory
Setting:
1
Description:
It allows the selection of the action to be executed by the device, if it is controlled via network and a communication
error is detected.
The following events are considered communication errors:
A128 alarm/F228 fault: Serial communication timeout.
The actions described in this parameter are executed by means of the automatic writing of the selected actions in
the respective bits of the interface control words. Therefore, in order that the commands are effective, it is necessary
that the device be programmed to be controlled via the used network interface (with exception of option “Causes a
Fault”, which blocks the equipment even if it is not controlled by network). This programming is achieved by means
of parameters P220 to P228.
Table 4.7: P313 options
Indication Description
0 = Inactive No action is taken and the drive remains in the existing status.
1 = Ramp Stop A stop command with deceleration ramp is executed and the motor stops according
to the programmed deceleration ramp.
2 = General Disable The drive is disabled by removing the General Enabling and the motor coasts to stop.
3 = Go to LOC The drive commands change to Local.
4 = LOC Keep Enab. The drive commands change to Local, but the status of the enabling and speed
reference commands received via network are kept, providing that the drive has been
programmed to use in Local mode the commands via HMI, or 3-wire start/stop and
speed reference via either HMI or electronic potentiometer.
5 = Cause Fault Instead of an alarm, the communication error causes a drive fault, so that a drive fault
reset becomes necessary in order to restore normal operation.
P314 - Serial Watchdog
Adjustable
Range:
0.0 to 999.0 s Factory
Setting:
0.0 s
Properties: cfg
Description:
It allows programming a time limit for the detection of serial interface communication error. If the frequency inverter
remains without receiving valid telegrams longer than the time programmed in this parameter, it will be considered
that a communication error has occurred, the alarm A128 will be showed on the HMI and the option programmed
in P313 will be executed.
After being powered up, the frequency inverter starts counting this time from the first received valid telegram. The
value 0.0 disables this function.
P316 - Serial Interf. Status
Adjustable
Range:
0 = Inactive
1 = Active
2 = Watchdog Error
Factory
Setting:
-
Properties: ro
CFW320 | 18

PARAMETERS
Description:
It allows identifying whether the serial communication presents errors.
Table 4.8: P316 options
Indication Description
0 = Inactive Serial interface without valid data traffic.
1 = Active Serial interface with valid data traffic.
2 = Watchdog Error The serial interface is active, but a serial communication error has been detected -
A128 alarm/F228 fault.
CFW320 | 19

OPERATION IN THE MODBUS RTU NETWORK – SLAVE MODE
5 OPERATION IN THE MODBUS RTU NETWORK – SLAVE MODE
The CFW320 frequency inverter has the following characteristics when operated as a slave in Modbus RTU network:
Network connection via RS485 serial interface.
Address, communication rate and byte format defined by equipment parameters.
It allows the CFW320 frequency inverter programming and control via the access to parameters.
It allows accessing all the markers and data used in the ladder program of the CFW320 frequency inverter.
5.1 AVAILABLE FUNCTIONS
In the Modbus specification are defined the functions used to access different types of data. In the CFW320, in
order to access those data the following services (or functions) have been made available:
Table 5.1: Supported Modbus Functions
Code Name Description
01 Read Coils Reading of bit blocks of the coil type
02 Read Discrete Inputs Reading of bit blocks of the discrete input type
03 Read Holding Registers Reading of register blocks of the holding register type
05 Write Single Coil Writing in a single bit of the coil type
06 Write Single Register Writing in a single register of the holding type
15 Write Multiple Coils Writing in bit blocks of the coil type
16 Write Multiple Registers Writing in register blocks of the holding register type
22 Mask Write Register Writing in holding register using mask
23 Read/Write Multiple registers Reading and writing in register blocks of the holding
register type
43 Read Device Identification Identification of the device model
5.2 MEMORY MAP
The frequency inverter CFW320 has different types of data accessible through the Modbus communication. These
data are mapped at data addresses and access functions as described in the following items.
5.2.1 Parameters
The CFW320 frequency inverter Modbus communication is based on the reading/writing of the equipment
parameters. All parameters of the equipment are available as 16-bit holding registers. The data addressing is
done with the offset equal to zero, which means that the parameter’s network address (Net Id) corresponds to the
register address. The Table 5.2 on page 20 illustrates the parameters addressing, which can be accessed as
holding register:
Table 5.2: Parameters Access - Holding Registers
Modbus data address
Parameter Decimal Hexadecimal
P000 0 0000h
P001 1 0001h
.
.
..
.
..
.
.
P100 100 0064h
.
.
..
.
..
.
.
It is necessary to know the device list of parameters to be able to operate the equipment. Thus, it is possible to
identify what data are needed for the status monitoring and the control of the functions. The main parameters are:
Monitoring (reading):
P680 (holding register address 680): Status word.
CFW320 | 20