Endress+Hauser MODBUS RS485 - Page 71

Proline Promag 53 MODBUS RS485 Operation
Endress+Hauser 71
Example
The following device parameters should be grouped via the auto-scan buffer and read out by the
master with just one request telegram:
•Volume flow → Register address 2009
• Totalizer 1 → Register address 2610
• Actual system condition → Register address 6859
1. Configuration of the scan list
• With the local operation or a configuration program (via the function matrix):
BASIC FUNCTION block → MODBUS RS485 function group → SCAN LIST REG. function
→ Entry of the address 2009 under SCAN LIST REG. 1
→ Entry of the address 2610 under SCAN LIST REG. 2
→ Entry of the address 6859 under SCAN LIST REG. 3
• Via the MODBUS master (the register addresses of the device parameters are written to the
registers 5001 to 5003 via MODBUS):
1. Write address 2009 (volume flow) to register 5001
2. Write address 2610 (totalizer 1) to register 5002
3. Write address 6859 (actual system condition) to register 5003
a0004416-en
Fig. 47: Configuration of the scan list via the MODBUS master
2. Access to data via MODBUS
By specifying the register start address 5051 and the number of registers, the MODBUS master can
read out the measured values with just one request telegram.
MODBUS RS485
Master
Slave
Data Data
RegisterValue
Scan List
1
2
3
No.
5001
5002
5003
Data
2009
2610
6859
Register
Register
Register Value
Auto-Scan Buffer
Data area
Access via MODBUS
register address
Measured values Data type Access
5051 Volume flow = 4567.67 Float Read
5053 Totalizer 1 = 56345.6 Float Read
5055 Actual system condition = 1 (system ok) Integer Read