Chengdi RS485 Pressure Gague Wiring Definition and MODBUS Protocol

Product catalog summary

Specifications:
The document outlines the wiring and data format for a pressure gauge using MODBUS protocol. The wiring includes connections for power (Brown: 12~24VDC, Blue: 0V), communication (White: 485A D+, Orange: 485B D-), and digital output (Black). The data format consists of an address, function, data, and CRC.

Register Address Description:
Various registers are described, including those for pressure values, output target values, upper and lower limit values, output modes, display color settings, unit settings, and reset settings. The document specifies the corresponding pressure values and settings for each register.

Communication Protocol:
The default baud rate is 19200 with 1 start bit, 8 data bits, 1 stop bit, and no parity bit. The pressure gauge address can be adjusted from 1 to 247, with a default value of 01H. Function codes for reading and writing registers are provided, including examples for commands and responses.

Procedures:
Instructions for changing the address, baud rate, stop bit, and verification code of the pressure gauge are detailed. These involve using the MODE key to navigate the MENU setting and adjusting values with the up and down keys.

Command Examples:
Examples of host commands and pressure switch returns are provided for different function codes, illustrating the structure of data exchanges in the MODBUS protocol.

Catalog excerpts

Chengdi RS485 Pressure Gague Wiring Definition and MODBUS Protocol-1

485CommunicationPressureGague MODBUSProtocolAndWiringInstructions Brown12~24VDCBlue :0V White 485A D+ Orange 485B D-BlackDigitalswitchingoutput Data CRC Address Funtion DataFormat 8bit 8bit n*2*8 bit 16bit SingleFrame Thedefaultbaudrateis19200,with1startbit,8databits,1stopbits,andnoparitybit. TheaddressofPressureGaguecanbeadjustedfrom1to247,withadefaultvalueof01(hexadecimal01H). Format FunctionCode RegisterAddressDescription: Address Corresponding PressureSwitch Ontologysettings Normallyopenand normallyclosed settingvalue Displayvalue ne-tuningsettings Microvalue shieldingfunction - 1013~1000 NC correspondingto - 101.3kPa~100kPa 0~1 Correspondingto Switchingoutput OUT1targetvalue correspondingto correspondingto upperlimitvalue out1_down_value~1.000MP out1_down_value~101.0kPa OUT1targetvalue correspondingto correspondingto lowerlimitvalue - 0.100MPa~out1_up_value - 101.0kPa~out1_up_value EASY,HYS,WCMP 0~3 Correspondingto R_ON,G_ON,RED,GREEN EASY,HYS,WCMP 0~3 Correspondingto R_ON,G_ON,RED,GREEN Read /write UNIT no.nc

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Chengdi RS485 Pressure Gague Wiring Definition and MODBUS Protocol-2

03HCommandExample Hostsend DriveAddress FunctionCode High-order Low-order High-order Low-order Low-order High-order Pressureswitchreturn DriveAddress 01H FunctionCode 03H DataQuantity 04H High-order 00H Data1 Low-order 00H High-order 00H Data2 Low-order 00H Low-order FAH CRC High-order 33H High-order Low-order High-order Low-order Low-order High-order Pressureswitchreturn DriveAddress 01H FunctionCode 04H DataQuantity 02H High-order 00H Data1 Low-order 00H Low-order B9H CRC High-order 30H High-order Low-order High-order Low-order Low-order High-order Pressureswitchreturn DriveAddress 01H FunctionCode...

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