Appendix C: Modbus Registers

Parameter Sets Available via MODBUS Protocol

The parameter sets available via the MODBUS protocol are listed below. The internal structure of all parameter sets is similar to that of the set described in Settings, except for the start address.

Setting	Description	Access	Addresses
Alterable settings	The parameters listed in Settings, that can be changed and enabled as described in Configuring EM-483 via the WEB-interface and MODBUS-interface	Only in setup, read or write mode	300 – 799, 5250 – 5499
Current settings	The parameters used at the moment	In any mode, read-only	2300 – 2799, 5500 – 5749
Saved settings	The set is saved regardless of whether the power is available and is used at startup	Only in setting mode, read-only	3300 – 3799, 5750 – 5999

Format of Parameters Presentation in MODBUS Registers

Parameter	Range of Values	Description	Number of Occupied Registers
Number	0 – 65535	Integer number (16 bits) in the standard range of the MODBUS register values	1
Number	0 – 4294967295 in two registers, the upper part is the first one	Integer number whose value may be greater than the MODBUS register limit (65535)	2
String of characters	In each register, ASCII is the character code or 0 (the end of the string)	A set of values, each of which is equal to code 1 of the character in ASCII coding. If a string is shorter than the greatest length, code 0 is placed after the last character	The longest string for the given parameter
IP address (IP mask)	One byte (0 – 255) in each register	A set comprised of four bytes of IPv4 address, left to right	4
MAC address	One byte (0 – 255) in each register	A set comprised of six bytes of MAC-48 address, left to right	6

Device Describing Parameters

Parameter	Description	Address
Type of the product	The code determining the MODBUS product at the manufacturer’s (33 – EM-483)	0
Software version	Version of the embedded software	1
Check code	CRC32 of the embedded software	2–3

Current Mode Parameters

Parameter	Values Range	Initial Value	Description	Address
Password entry	String of characters	0	When entering a valid password, the client is granted the appropriate permission (registers 510 – 549). When entering an empty string, the client’s rights are reset to the level of rights at the time of connection	100–119
Control command	0–444, 64893, 65397, 65407 (writing in the setup mode)	0	0: no action; 1: «Restart» – means EM-483 restart; 2: «Save» – means saving the altered settings; 3: «Apply» – means to apply settings without restart (accessible only for MODBUS parameters and user’s ones); 4: «Save and apply» – means the same as orders 2 and 3 sent one after another; 6: «Export» – means read the saved settings and write them into the file; 7: «Import» – means read the settings from the file and save them in the internal memory; 9: «Cancel» – means read the saved settings; 51: «Apply for MODBUS» – means apply the settings to the MODBUS network and MODBUS TCP; 59: «Apply to user’s» – means apply the settings to the user’s register area; 444: «Restore factory settings» – means reset the settings to their factory values; 64893: «Download updates» − start downloading the latest firmware version from the cloud server to the downloaded firmware file; 65397: «Update firmware» − program from the downloaded file; 65407: «Return firmware» − program from the factory file	120

Current State Parameters

Parameter	Description	Address
Mode (for more details, see reg. 122)	0: User’s mode; 1: Setting mode	121
Access mode flags	See Access Mode Flags table below	122
Time, minutes	Number of minutes after start-up	123–124
Clients number	Number of busy connections	125
Clients limit	Total number of possible clients	126
Load RS-485, requests/sec	Number of requests sent via RS-485 per second	127
RS-485 useful load, requests/sec	Number of answers without errors via RS-485 per second	128
RS-485 load per second, %	RS-485 business within the last second in consideration of the RS-485 rated speed and silence time	129
RS-485 load during a minute, %	RS-485 business within the last minute	130
RS-485 load during 5 minutes, %	RS-485 business with the last five minutes	131
MODBUS TCP load, requests/sec	Number of requests received from the clients via MODBUS TCP per second	132
MODBUS TCP useful load, requests/sec	Number of answers without errors sent to clients via MODBUS TCP per second	133
Ethernet load, ×100 kB/s	Wire channel load with the Ethernet switched on	135
Maximum clients	The maximum number of simultaneously connected clients from the moment of start-up	136
Maximum MODBUS TCP load, requests/sec	The maximum number of requests received from clients via MODBUS TCP within one second from the start-up moment	137
Maximum RS-485 load, %	The maximum RS-485 load during 5 minutes after start-up	138
Ethernet current IP-address	IP-address, at which EM-483 is accessible on the Ethernet network	140 – 143
Ethernet current MAC-address	MAC-address, at which EM-483 is identified on the Ethernet network	144 – 149
Time before connection to the data collection server, sec	0: connection with the data collection server is established; 1: connecting to the data collection server; 2 – 65534: the number of seconds prior to reconnection; 65535: connection to the server is not used	165
Number of programmed restarts	The number of restarts according to the user’s set-up during the whole time of operation	166
Number of critical errors	The number of noted errors (malfunctions) that caused the product restart during the whole time of operation	167
Total time of work, min	Number of the product operating minutes during the whole time of operation	168 – 169
Time, sec	Number of seconds from start-up	170 – 171
Power voltage, mV	Voltage on the product power supply terminals	175
Time prior to connection to the 1st remote server, sec	0: connection with the remote server is established; 1: connecting to a remote server; 2–65534: number of seconds prior to reconnection; 65535: connection to the remote server is not used	176
State of connection to the 1st remote server	0: no connection; 1: Ethernet connection is established	177
Time prior to connection to the 2nd remote server, sec	Similarly, reg. 176	240
State of connection to the 2nd remote server	Similarly, reg. 177	241
Firmware update download status	See Firmware Download Status Flags table below	2004
Firmware file download progress, × 0.01%	Downloaded part of the full file size. 10000 − file is completely downloaded	2005
Title of the downloaded firmware file	Version identifier string, e.g. “EM-483 ver.6”. Empty string − file not checked or incorrect	2030 – 2061
User’s parameters of state	Reset to 0 at restart. Can be used for temporary storage and transfer to the server of data received from connected clients	5000 – 5249

Access Mode Flags (Register 122)

Bit	Description
Bit 0	The ability for the connected client to obtain permission (using a password) for requests to get reading functions of devices via MODBUS: 0: permission cannot be obtained; 1: permission is issued upon the password is provided
Bit 1	Permission for the connected client to request device read functions via MODBUS: 0: no permission; 1: permission is given
Bit 2	The ability for the connected client to obtain permission (using a password) for requests for write and device management functions via MODBUS: 0: permission cannot be obtained; 1: permission is issued upon the password is provided
Bit 3	Permission for the connected client to request for write and device management functions via MODBUS: 0: no permission; 1: there is a permission
Bit 4	The ability for the connected client to obtain permission (using a password) to access the EM-483 registers, except for the registers of version, password, mode, and access flags: 0: permission cannot be obtained; 1: permission is issued after the password is provided
Bit 5	The ability for the connected client to obtain permission (using a password) to access the EM-483 registers, except for the registers of version, password, mode, and access flags: 0: no permission; 1: permission is issued
Bit 6	Always 1
Bit 7	Permission for the connected client to configure EM-483 (similar to register 121): 0: no permission; 1: there is a permission

Firmware Download Status Flags (Register 2004)

Bit	Description
Bit 1	Busy indication: 0 − waiting for command; 1 − receiving file
Bit 2	Receiving updates error: 0 − no stop with error; 1 − error
Bit 3	Connection to the server: 0 − no connection with the server; 1 − connection established
Bit 4	Retrieving file data: 0 − no file data; 1 − data downloaded
Bit 6	File download completion: 0 − file has not been downloaded; 1 − file has been completely downloaded
Bit 7	File correctness: 0 − no confirmation; 1 − file is correct

Settings

Ethernet Network

Parameter	Range	Factory Value	Description	Address
Static IP address	IP-address	192.168.0.111	If the dynamic addressing is disabled or inaccessible, the IP address on the Ethernet network is equal to this value	300 – 303
Subnet mask	IP mask	255.255.255.0	This is used only together with the static IP address	304 – 307
Gateway	IP-address	192.168.0.1	This is used only together with the static IP address for the connection with other networks or as the address of DNS/DHCP servers	308 – 311
DHCP dynamic addressing mode	0 – 2	1	0: the specified values of the gateway, mask, and static IP address are used for addressing in Ethernet; 1: The product uses the network’s DHCP server to determine the gateway, mask, and masked part of the IP address that denotes the network. The remaining part of the address is used from the specified static address. If the server is unavailable, static addressing values are used; 2: The product uses the DHCP server to determine the gateway, mask, and IP address	312
Switch on the IP address filter of the DHCP server	0 – 1	0	This is used for dynamic addressing. 0: receiving the addressing data from the DHCP server that answered first; 1: receiving the data of addressing only from the DHCP server with the IP address of the gateway	313
Switch on the use of the gateway DNS server	0 – 1	1	This is used, if DHCP is inaccessible (switched off). 0: Gateway DNS is not used; 1: Gateway DNS is used to identify IP addresses of other servers, if they are set by host names	314
IP address of DNS server	IP-address	8.8.8.8	This is used, if DHCP is inaccessible (switched off). When it is switched on and the gateway DNS server is used, the IP-address of the DNS additional server is set	315 – 318
IP address of the DNS additional server	IP-address	0.0.0.0	This is used, if DHCP is inaccessible (disabled). 0.0.0.0: is not used	319 – 322
Switch on the MAC address redefinition	0 – 1	0	0: the value unique for each product is used as the MAC address; 1: the manually set MAC address is used	323
Ethernet MAC address set manually	MAC address	Unique for each product	This is used when MAC manual address is on for identification of the product on the Ethernet network	324 – 329

MODBUS Network

Parameter	Range	Factory Value	Description	Address
Optional MODBUS RTU/ASCII connection port via TCP or in tunnel mode	0 – 65535	0	Used for external connection to EM-483 via Ethernet for exchange via MODBUS RTU, MODBUS ASCII protocol or in tunnel mode. The format is the same as used for RS-485 interface (reg. 463, 637). For MODBUS − only packets containing whole frames are processed, if TCP packets are fragmented, the connection is closed. 0: connection is not used	335
Connection port via MODBUS TCP	1 – 65535	502	This is used for external connection to EM-483 via Ethernet for exchanging with the use of MODBUS TCP protocol	450
Disconnect inactive clients	0 – 1	1	0: incoming connection is supported regardless of the time between requests from the client; 1: disconnect the clients, from whom no requests have been received longer than the set time	451
The longest request wait time, sec	0 – 600000	90	This is used, if the disconnection of inactive clients is selected	452 – 453
Enable queue for the last busy MODBUS TCP connection	0 – 1	0	0: MODBUS TCP connection is supported regardless of the connection hold time; 1: If all MODBUS TCP connections are busy, the new client requesting a connection can be connected instead of the last connected client if the connection hold time is longer than the specified one	454
Maximum hold time for the last MODBUS TCP connection, msec	0 – 600000	60000	This is used, if the queue for the last MODBUS TCP connection is enabled	455 – 456
Native MODBUS Identifier EM-483	0 – 247	111	0: All MODBUS TCP requests are forwarded to the MODBUS network, the product registers are not available via MODBUS TCP; 1-247: The product responds to MODBUS TCP requests with this MODBUS ID without forwarding them to the MODBUS network	457
RS-485 data transfer rate, bit/s	75 – 281250	9600	This is used when exchanging with devices via RS-485, the same value for devices on the same bus	458 – 459
Enable byte format selection in RS-485 transmissions	0 – 1	1	This is used when exchanging with devices via RS-485, the same value for devices on the same bus. 0: This is not used, the byte ends with 2 stop bits; 1: The byte format is selected from register 461	460
Byte format in RS-485 transmissions	0 – 5	5	This is used when communicating with devices via RS-485 only if byte format selection is enabled. The same value for devices on the same bus. 0: “EVEN” – 1 parity bit and 1 stop bit; 1: “ODD” – 1 parity bit and 1 stop bit; 2: “0” (“SPACE”) – 1 zero bit and 1 stop bit; 3: “1” (“MARK”) – 1 single bit and 1 stop bit (similar to the mode with two stop bits); 4: “MISSING” – no parity bit, 1 stop bit; 5: “AUTO-STOP” – no parity bit, 2 stop bits in the sent bytes, 1 stop bit in the received ones (devices with 1 and 2 stop bits can be connected at the same time)	461
Wait time for the start of the MODBUS RTU response, msec	0 – 60000	200	Used for RS-485 transmissions in MODBUS RTU mode or tunnel mode. After sending the request, if the first byte of the response was not received within this time interval, the waiting for the response is terminated. The response is always expected to be at least the time of silence between frames (the time of silence depends on the transfer rate and is equal to the transfer time of 3.5 bytes or 1.75 ms for speeds over 19,200 bps)	462
Enable ASCII exchange mode in the MODBUS network	0 – 6	2	MODBUS exchange mode, the same value for devices on the same bus. 0: RTU exchange mode (format: 1 start bit, 8 data bits, 2 stop bits, parity bit and stop bit, or only 1 stop bit – only 10 to 11 bits); 1: ASCII exchange mode (format: 1 start bit, 7 data bits, 2 stop bits or parity bit, and stop bit – 10 bits in total). Non-standard byte formats (register 461, values 4 and 5) are not available, but the format 3 (2 stop bits) is used instead; 2: similar to “0”, but with increased silence time between frames by 2 times; 3: similar to “2”, but 4 times; 4: similar to “2”, but 8 times; 5: similar to “2”, but 16 times; 6: similar to “2”, but 32 times	463
Waiting time for the next MODBUS ASCII character, ms	0 – 60000	1000	Used for RS-485 transmissions in MODBUS ASCII mode. When receiving a response, if the next byte of the response was not received during this time interval, the waiting for the response is terminated. The waiting time is always equal at least to the transmission time of one character (depends on the transmission speed)	464

Connecting to the Data Collection Server

Parameter	Range	Factory Value	Description	Address
Data collection server connection mode	0 – 2	1	0: connection to the server is not used; 1: connection to the server is established and maintained through the specified server connection port (the port on the server side); 2: passive mode, the server is expected to connect via the specified server connection port (the port is on the EM-483 side)	465
Server connection port	0 – 65535	20502	The port that is accessed by the party establishing the connection between the EM-483 and the server (see register 465)	466
Waiting time for a response from the server, sec	0 – 3600	120	0: server silence time is unlimited; 1-3600: the maximum server silence time, after which the connection will be terminated and must be re-established	467
Waiting time before reconnecting to the server, sec	0 – 30000	15	This is used when connecting to the server (except for the “2” mode). After the connection to the server is lost, the reconnection will be made after the specified waiting time (after starting the product, the first connection is made in fixed time – 5 seconds)	468
Enable setting the server address with a text string	0 – 1	1	This is used when connecting to the server (except for mode “2”). 0: the connection is made to the server with a fixed IP address given in registers 470-473; 1: the connection is made to the server with the name specified in registers 474-509	469
Server IP address	IP address	0.0.0.0	This is used when connecting to the server (except for the mode “2”), if setting the server address with a text string is disabled. The IP address of the remote server, connection to which is supported	470 – 473
Server address	String of chars	modbus.overvis.com	This is used when connecting to the server (except for mode “2”), if setting the server address with a text string is enabled. The address of the remote server, connection to which is supported. The address can be a string up to 36 characters long. There can be no spaces in the string	474 – 509

Protection

Parameter	Range	Factory Value	Description	Address
The specified password for entering the setup mode	String of chars	11111	This is used to access the configuration mode. The password can be a string of 5 to 10 characters long. There should be no spaces in the string	510 – 519
Set password for allowing MODBUS writing to devices via RS-485	String of chars		This is used to access devices connected to EM-483 to request the write or control functions that can change the state of these devices. The password can be a string up to 10 characters long. There should be no spaces in the string	550 – 559
The set password for allowing MODBUS reading	String of chars		This is used to access devices connected to EM-483 to request read functions or to access EM-483 registers other than version, password, mode, and flag registers. The password can be a string up to 10 characters long	560 – 569
Enable MODBUS write protection mode	0 – 1	0	0: write protection is controlled by other parameters (password) or disabled; 1: any function requests other than MODBUS functions 1, 2, 3, 4, 7, 17, 20 are blocked	572
Enable MODBUS read protection mode	0 – 1	0	0: read protection is adjusted using other parameters (password) or disabled; 1: requests for MODBUS functions 1, 2, 3, 4, 7, 17, and 20 are blocked, except for read by function 3 of registers of the version, mode and flags	573

Miscellaneous

Parameter	Range	Factory Value	Description	Address
Enable the product automatic restart	0 – 1	1	0: periodical restart is disabled; 1: the product gets restarted in a set period of time	630
Restart period, min	5 – 7200	120	This is used, if the automatic restart is enabled	631
Enable restart mode automatically only when there are no connections	0 – 1	1	This is used, if the automatic restart is enabled. 0: the product is restarted after a set period of time from the start-up; 1: the product is restarted after a set time interval from the last MODBUS transmission	632
MODBUS exception code generated when access is denied	0 – 255	1	0: if access to MODBUS registers is denied, no response is returned to the client; 1 – 255: if access is denied to the client that sent the request, this exception code is returned	633
MODBUS exception code generated when there is no answer	0 – 255	11	0: if there is no response from the request recipient (Gateway Timeout), the response is not returned to the client; 1 – 255: if there is no response from the request recipient, this exception code is returned to the client	634
MODBUS exception code generated when there is no connection to the request destination	0 – 255	10	0: if there is no response from the request recipient (Gateway Path Unavailable), the response is not returned to the client; 1 – 255: if there is no response from the request recipient, this exception code is returned to the client	636
RS-485 transmission mode	0 – 2	0	0: master mode (Master). RS-485 is used to send requests; 1: slave mode (Slave). RS-485 is used to receive requests from an additional client; 2: tunnel mode, used for data transmission “as is”, without protocol verification	637
The first MODBUS-identifier of the RS-485	1 – 255	1	The parameters define the range of MODBUS identifiers used on RS-485. In master mode, requests with addresses in this range (as well as broadcasts with address 0) are routed via RS-485. In slave mode, requests with addresses in this range (as well as broadcast and EM-483 requests) are received over RS-485	638
The last MODBUS identifier of the RS-485	1 – 255	255	See register 638	639

Connecting to the First Remote Server

Parameter	Range	Factory Value	Description	Address
Connecting to the First Remote Server	IP address	192.168.0.112	This is used when redirecting requests to a remote server is enabled. This is the IP address of the remote server, to which the connection is supported	640 – 643
Remote server connection port	0 – 65535	502	Used when redirecting requests to a remote server. The port of the remote server to which the connection will be established	644
Wait time for a response from the remote server, msec	0 – 60000	1000	This is used when redirecting requests to a remote server. After sending the request, if the correct response was not received during this time, the waiting for the response is terminated	645
Wait time before the reconnection to the remote server, msec	0 – 240	20	This is used when redirecting requests to a remote server. After the connection with the server is lost, the reconnection will occur in the set wait time	646
Remote server connection mode	0 – 3	0	0: remote server is not used; 1: connect to the server in MODBUS TCP mode; 2: similarly to 1 with virtual identifiers*; 3: connect to the server in tunnel mode	647
The first MODBUS-identifier of the remote server	1 – 255	1	This is used when redirecting requests to the remote server. The range of the MODBUS identifiers is used on the remote server. Requests with addresses in this range (and broadcasts with address 0) are sent to the MODBUS TCP remote server	648
The last MODBUS identifier of the remote server	1 – 255	255	See register 648	649

* In virtual identifiers mode, before redirecting a request to a remote server MODBUS TCP, the virtual identifier of the destination from the request is replaced with the real one so that the numbering in the server range starts with 1. For example, for the range 15-17, the virtual ID 16 will be replaced with the real one 2. The broadcast ID 0 is processed without changes.

Connecting to the Second Remote Server

Similar to registers 640–649, with the factory value of the remote server IP address being 192.168.0.113.

Parameter	Address
Remote server IP address	760 – 763
Remote server connection port	764
Wait time for response, msec	765
Wait time before reconnection	766
Remote server connection mode	767
First MODBUS-identifier	768
Last MODBUS identifier	769

Connecting to the Third Remote Server

Similar to registers 640–649, with the factory value of the remote server IP address being 192.168.0.114.

Parameter	Address
Remote server IP address	770 – 773
Remote server connection port	774
Wait time for response, msec	775
Wait time before reconnection	776
Remote server connection mode	777
First MODBUS-identifier	778
Last MODBUS identifier	779

Connecting to the Fourth Remote Server

Similar to registers 640–649, with the factory value of the remote server IP address being 192.168.0.115.

Parameter	Address
Remote server IP address	780 – 783
Remote server connection port	784
Wait time for response, msec	785
Wait time before reconnection	786
Remote server connection mode	787
First MODBUS-identifier	788
Last MODBUS identifier	789

Connecting to the Fifth Remote Server

Similar to registers 640–649, with the factory value of the remote server IP address being 192.168.0.116.

Parameter	Address
Remote server IP address	790 – 793
Remote server connection port	794
Wait time for response, msec	795
Wait time before reconnection	796
Remote server connection mode	797
First MODBUS-identifier	798
Last MODBUS identifier	799

User’s Settings

Parameter	Range	Factory Value	Description	Address
User’s settings and stored values	0 – 65535	0	May be used for storing any identification or other data	5250 – 5499

Virtual Registers

Parameter	Description	Address
Virtual registers	When accessing these registers, EM-483 transfers the request to another device. The real MODBUS identifier from the range 1-32 and the register addresses (in the range 0-999) depends on the virtual register address: <virtual register address> = 5000 + 1000 × <MODBUS identifier> + <real register address>	6000 – 37999