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Parameter | Meaning | Unit | Default value | ||||||
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| Maximum count of request retries. If no response returns after a request had been sent, the station's status will change to a communication error. | - | 2 | ||||||
| Timeout before resending a request if no response has been received. | s | 0.1 | ||||||
| The delay after sending the request and before reading the response. | s | 0.1 | ||||||
| The delay between the response readings. | s | 0.1 | ||||||
| The maximum number of retries of the response reading. | - | 20 | ||||||
| "Start silent interval" before the beginning of the transmission in RTU mode. | ms | 50 | ||||||
| "Stop silent interval" after ending of the transmission in RTU mode. | ms | 50 | ||||||
| Byte order in Little-endian mode for 4-byte variables. The individual options indicate in which bytes (1-lowest, 4-highest) the individual bytes from the communication will go:
| - | 2143 | ||||||
| Special byte mode of transmission in which the values of registers have a length of 1 byte and not 2 bytes as it is defined in Modbus protocol specification. | YES/NO | NO | ||||||
| Special variable mode of transmission in which the values of registers have variable lengths. The setting of Variable mode: Note 1: Variable and byte modes are incompatible and only one of them can be enabled. | OFF Little endian Big endian | OFF | ||||||
| Logging of detailed debug information about communication in the line log. | YES/NO | NO | ||||||
| Protocol mode: RTU or ASCII. Note: In the case of "MODBUS over TCP/IP", the parameter value is ignored and Protocol Mode=RTU is used. | RTU ASCII | RTU | ||||||
| Sets an address model of MODBUS protocol: MODBUS PDU data are addressed from 0 up to 65535. MODBUS data Model data are addressed from 1 up to 65536. Note: MODBUS PDU is a default value. If the MODBUS data Model is set, the object with the address X is addressed as X-1 in MODBUS PDU. After you change this parameter, a restart of the respective communication process was required in the past (KOM binaries older than May 27, 2021). | MODBUS PDU MODBUS data Model | MODBUS PDU | ||||||
| Select a variant of the protocol in case of TCP/IP communication: "MODBUS TCP" is a variant of communication without control checksum. Safeguarding is done by the underlying TCP protocol. "MODBUS over TCP" is a variant where a payload is MODBUS RTU data containing a checksum. | "MODBUS TCP" "MODBUS over TCP" | "MODBUS TCP" | ||||||
| Maximum count of registers that are read by one request. | - | 100 | ||||||
| Maximum count of bytes that are required by one request (only in "Byte mode"). | - | 100 | ||||||
| If a value of the integer type (Holding Registers, Input Registers) is assigned to an I/O tag of the Di or Dout type, this is done by comparing the read value with zero. If the value is zero, the value of the I/O tag is False, otherwise True. The Bool Mask parameter allows specific bits to be filtered out before the comparison is made, based on a bitmask specified as a hexadecimal number (the leftmost byte is the highest). The bitmask FF FF FF FF means that all bits are considered (for 1- and 2-register integer addresses). | - | FF FF FF FF | ||||||
| To read This parameter is used to avoid reading the values from addresses that are not configured is not allowed. Description and example: | YES/NO | NO | ||||||
| If this parameter is set to YES, then an extra check is performed when receiving a response to a read request: the length of received data is checked whether it matches the number of registers in a read request:
| YES/NO | NO | ||||||
| If the parameter is set to YES, then a single request (which contains the total number of registers) is used. It is necessary that the I/O tags are defined for all addresses 0..N. | YES/NO | NO |
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Independent addressing with the address size of 2 bytes, i.e. addresses from 0 up to 65535 (so-called MODBUS PDU addressing model), is in an address space of each type of register. Some devices work with address space starting with 1 (so-called MODBUS Data Model). In this case, it is necessary to deduct 1 in the address at configuration I/O tags in the D2000 system or change the setting of the parameter Addressing model to the MODBUS data Model.
The I/O tag with an address starting with %IGNORE will be ignored.
I/O tag address can be in a basic or extended format (for a variable mode).
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Address format is [xN].[I|U|F|B|C|T][b]RdFn[-WrFn].Address[.BitNr] in which:
- xN indicates the number of bytes that read or write. Valid values for N are 1, 2, 4, 8 (in combination with I, U, F), 6 for T type, and an arbitrary number for C type.
- A letter defines the type of I/O tag. Besides standard I, U, F, B, two extra types have been added:
- C - text string of fixed length (e.g. x10.C3.1001 is a 10-character string on address 1001)
- T - time stamp with length of 6 bytes (ss:mi:hh dd:mm:yy)
- The meaning of other parameters is in compliance with the standard mode.
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- Ver. 1.0 - November 27th, 2006 - document creating.
- Ver. 1.1 - November 21st, 2007 - document update.
- Ver. 1.2 - April 24th, 2009 - document update.
- Ver. 1.3 - November 3rd, 2010 - document update.
- Ver. 1.4 - December 6th, 2010 - document update.
- Ver. 1.5 - September 5th, 2022 - document update (support for 8-byte values in the extended format).
- Ver. 1.6 - September 7th, 2022 - document update (added parameter "Dummy Request Mode").
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