Sensia CamCor Manuale utente
CamCor™
Modbus Protocol Manual
Manual No. 50284150, Rev. 01
Important Safety Information
Symbols and Terms Used in this Manual
!WARNING: This symbol identies information about practices or circumstances that can lead to personal injury or
death, property damage, or economic loss.
Important Indicates actions or procedures which may affect instrument operation or may lead to an instru-
ment response which is not planned.
Symbols Marked on Equipment
Attention! Refer to manual Protective (earth) ground
Technical Support Contact Information
Global headquarters:
Sensia LLC
200 Westlake Park Blvd
Houston, TX 77079
CamCor is a trademark of Sensia.
Modbus is a registered trademark of the Modbus Organization, Inc.
All Rights Reserved.
Manual No. 50284150, Rev. 01
September 2015
Contents
Important Safety Information .................................................................................................................................................. ii
Section 1—Modbus Protocol........................................................................................................................... 5
Introduction .............................................................................................................................................................................5
Communications .....................................................................................................................................................................5
Optional Modbus Communication Baud Rate Setting .....................................................................................................5
Standard Modbus Function Codes ..................................................................................................................................6
Exception Response .......................................................................................................................................................6
Slave Addresses..............................................................................................................................................................6
Section 2—Data Types ..................................................................................................................................... 9
Data Formats ..........................................................................................................................................................................9
Unsigned Short Integer ...................................................................................................................................................9
Packed ASCII ..................................................................................................................................................................9
Section 3—CamCor Modbus Register Maps.................................................................................................11
Using CamCor Modbus Maps .............................................................................................................................................. 11
Access Types ................................................................................................................................................................ 11
CamCor-Specic Modbus Protocol Constraints ............................................................................................................ 11
Updating Intervals ......................................................................................................................................................... 11
Modbus Registers................................................................................................................................................................. 11
Device and System Information .................................................................................................................................... 11
Alarm Status Information ...............................................................................................................................................12
Communications Alarm Counter....................................................................................................................................12
Device, Sensor and Slave Address Conguration.........................................................................................................13
Damping Time Conguration .........................................................................................................................................14
Output Conguration .....................................................................................................................................................14
Density Conguration ....................................................................................................................................................16
Alarm/Status Conguration ...........................................................................................................................................16
Flow Conguration ........................................................................................................................................................17
Maintenance Conguration ...........................................................................................................................................17
Security Conguration ...................................................................................................................................................17
Calibration and Testing ..................................................................................................................................................18
Holding Registers ..........................................................................................................................................................18
Section 4—Reference Tables ........................................................................................................................ 23
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CamCor™Modbus Protocol Table of Contents
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iv
Table of Contents CamCor™Modbus Protocol
Section 1—Modbus Protocol
This manual is for use with maintenance board rmware version 3.05.
Introduction
The communications protocol for CamCor CT Series and PRO Series is in accordance with Modicon, Inc. RTU Mode
Modbus as described in Modicon Modbus Protocol Reference Guide, PI-MBUS-300 Rev. J, June 1996. All registers are
implemented as 4X or holding registers. Reading of registers is implemented via Function Code (03H) (Read Holding
Registers). Writing to registers is implemented via Function Code 16 (10H) (Preset Multiple Registers).
Communications
CamCor’s Modbus communications allow host devices (PC, sequencer, etc.) to connect to slave devices via RS-485 con-
nection. Modbus communication is based on the Master-Slave system, where host devices are designated as “master”
and the Coriolis meter(s) is designated as “slave.” The system is Modbus-protocol compliant. Contact the host device
service provider for assistance with host software.
Caution If the CamCor meter is installed in a control system, place the control system in manual operating
mode before making changes to the CamCor meter conguration. Failure to do so may cause er-
ratic and undesired responses from valves or other devices controlled by the system.
Consult Table 1.1—Communication Specications below for CamCor Coriolis meter communication specications.
Table 1.1—Communication Specications
Specication Description
Communication System RS-485 Multidrop-compliant Master/Slave System
Full-duplex/Half-duplex Half-duplex
Baud Rate 9600, 19200, 38400 (shipped from Factory at 9600)
Slave Address 1
Data Bits 8
Parity Odd
Stop Bit 1 Bit
Flow Control None
Communication Timeout 200 ms
Transmission Length (Maximum) 0.75 miles (1.2 km) (depending on service environment)
Number of Devices on Each Node
(Maximum)
32
Optional Modbus Communication Baud Rate Setting
A CamCor meter purchased with the Modbus Communication option is shipped with the baud rate set to 9600. The baud
rate is adjustable using the SW3-1 and SW3-2 switches on the maintenance board (Figure 1.1, Page 6) located in the
transmitter body. (For more information about maintenance board access and switch locations, see the CamCor Hardware
Manual.) See Table 1.2—Baud Rate Switch Settings below to identify baud rate settings based on switch position:
Table 1.2—Baud Rate Switch Settings
Baud Rate SW3-1 Setting SW3-2 Setting
9600 Off Off
19200 On Off
38400 Off On
5
CamCor™Modbus Protocol Section 1
Baud Rate SW3-1 Setting SW3-2 Setting
Do Not Set On On
Figure 1.1—Maintenance board switch locations and on/off positions
Standard Modbus Function Codes
The Modbus functions supported by CamCor Coriolis meters are as follows:
Function Code Description
03 (03H) Read Holding Registers
16 (10H) Preset Multiple Registers
Exception Response
If the device receives an unsupported function code in a query message, the device responds with an exception message.
For example, if the query message contains Function Code “11,” an unrecognized code, the function code on the
response message will be changed to the unexpected value code and “0x80,” or “0x91” in this case (original Function
Code + 80). The data value contains the exception code 0x02.
Slave Addresses
Allowed Slave Addresses
Slave devices are shipped from the factory with a slave address of “1.” Typically, each slave device should be assigned a
unique slave address. Allowed slave addresses range from 1 to 255. Slave Address “0” broadcasts messages to all slave
devices and is only available for Function Code 16. If the broadcast message contains valid data, the device is updated
and no response is sent to the host system. For information about invalid message handling, see Exception Response.
6
Section 1 CamCor™Modbus Protocol
Resetting an Unknown Slave Address
If you do not know the slave address of a device to be connected to the CamCor meter, you can reset it using the follow-
ing procedure:
WARNING Do not use this query while more than one slave is connected. In a multipoint drop connection
setup, all connected slaves share the same address; therefore, resetting the slave address will
assign the same address to all slave devices.
1. Establish a point-to-point connection between the slave device and the CamCor meter.
2. Send the following information:
– Broadcast slave address 0 (0x00)
– Function Code 16 (0x10)
– Register 167 (0x00A7)
– Data value to be written (in this example, Slave Address 1 = 0x0001)
– Data validity check—CRC (0xB1FB)
The entire query string appears as follows:
0x001000A70001B1FB
Note The “0x” prex is used only with the rst 4-digit character string, and is dropped from the remaining character
strings. See Unsigned Short Integer, Page 9 for more information.
7
CamCor™Modbus Protocol Section 2
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8
Section 2 CamCor™Modbus Protocol
Section 2—Data Types
Data Formats
Various data types are implemented in the CamCor CT Series and PRO Series Coriolis meters. The following table lists
the formats and the numbers of bytes and registers associated with each type.
Table 2.1—CamCor Data Formats
Data Format Data Type Byte Count Register Count
16-bit Floating Point (FP) 4 2
Unsigned Short Integer (U8) 2 1
Unsigned Integer (U16) 2 1
Unsigned Long Integer (U32) 4 2
Packed ASCII Packed ASCII (PAC) See Packed ASCII below
The word ordering for multiple register data types, such as oating-point numbers or long integers, places the most sig-
nicant word rst in the message.
Unsigned Short Integer
The protocol for the CamCor Coriolis meters is based on a 16-bit data format. The value for “U8–Unsigned Short Inte-
ger” is appended with 0x00. For example, if the value stored on the device is 125 (0x7D), the Standard Modbus Function
Code 3 response is “0x007D.”
Packed ASCII
On CamCor meters, Packed ASCII uses three bytes to store four characters. For example, character string “ABCD” is
stored as “0x0420C4” in Packed ASCII.
Table 2.2—CamCor Packed ASCII Code
Data Format Data Appearance
Byte 0x04 0x20 0xC4
Bit 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 1 1 0 0 0 1 0 0
Character* A(1) B(2) C(3) D(4)
*The value inside parentheses is the Packed ASCII Code.
9
CamCor™Modbus Protocol Section 2
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10
Section 2 CamCor™Modbus Protocol
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