Proline Promass 83E/F/O Modbus RS485 Operating Instructions

Proline Promass 83 Modbus RS485Operation5.5.7 Modbus auto-scan bufferFunction descriptionThe Modbus master uses the request telegram to access the device parameters (data) of themeasuring device. Depending on the function code, the master gains read or write access to a singledevice parameter or a group of consecutive device parameters. If the desired device parameters(registers) are not available as a group, the master has to send a request telegram to the slave foreach parameter.The measuring device has a special storage area, known as the auto-scan buffer, for groupingnonconsecutive device parameters. This can be used to flexibly group up to 16 device parameters(registers). The master can talk to this complete data block by means of just one request telegram.Structure of the auto-scan bufferThe auto-scan buffer consists of two data records, the configuration area and the data area. In theconfiguration area, a list known as the scan list specifies which device parameters should begrouped. For this purpose, the corresponding register address, e.g. the register address 2007 formass flow, is entered in the scan list. Up to 16 device parameters can be grouped.The measuring device cyclically reads out the register addresses entered in the scan list and writesthe associated device data to the data area (buffer). The request cycle runs automatically. The cyclestarts again when the last entry in the scan list has been queried.By means of Modbus, the grouped device parameters in the data area can be read or written by themaster with just one request telegram (register address 5051 to 5081).Configuration of the scan listDuring configuration, the Modbus register addresses of the device parameters to be grouped mustbe entered in the scan list. The scan list can contain up to 16 entries. Float and Integer-type deviceparameters with read and write access are supported.The scan list can be configured by means of:1. The local display or a configuration program (e.g. FieldCare).The scan list is configured here by means of the function matrix:BASIC FUNCTION Modbus RS485 SCAN LIST REG. 1 to SCAN LIST REG. 162. The Modbus master.Here, the scan list is configured via the register addresses 5001 to 5016.Scan listNo.Modbus configurationRegister address(data type = Integer)Configuration vialocal operation / configuration program(BASIC FUNCTION Modbus RS485 )1 5001 SCAN LIST REG. 12 5002 SCAN LIST REG. 23 5003 SCAN LIST REG. 34 5004 SCAN LIST REG. 45 5005 SCAN LIST REG. 56 5006 SCAN LIST REG. 67 5007 SCAN LIST REG. 78 5008 SCAN LIST REG. 89 5009 SCAN LIST REG. 910 5010 SCAN LIST REG. 1011 5011 SCAN LIST REG. 1112 5012 SCAN LIST REG. 12Issue/Rev. 0.2 (12/12) MN0M030 • Page 49