VP instruments VPLog-i-R, Руководство пользователя

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© 2020 Van Putten Instruments BV | MAN-VP-LOGR-UK | Revision: 2001 | Date: 01-10-2020
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Modbus settings
The following table holds the default communication parameters for modbus.
Parameter Description
Modbus Address 1
Baudrate 38400 baud
Parity No parity bit is used.
Stop-bits 1 stop bit is used.
Modbus registers
The following is an overview of the available modbus registers.
Name Register Description Units
I 50Hz 1 Current at base frequency 0.1 AAC
I RMS 2 True RMS current 0.1 AAC
Frequency 3 Frequency 0.01 Hz
Protocol functions
For reading the 16 bit values, modbus supports the commands “Read Holding Registers” (0x03).
When addressing registers, the command contains the address minus 1, for instance registers 1..3
are addressed as 0..2.
The VPLog-i-R also supports the modbus scan protocol. This allows to change the modbus settings
and to request extra information from the module.
Modbus example
Example 1
The following example contains a request and response for 2 registers starting at register 2 (RMS
c frequency).
Request : 01 03 00 01 00 02 95 CB
Response: 01 03 04 13 88 13 88 73 CB
Data bytes Description
Request
01 modbus address VPLog-i-R
03 Function
00 01 Starting register
00 02 Register count
95 CB CRC
Response
01 VPLog-i-R modbus address
03 Function
04 Byte count