Universal Flow Skid
Reads from either a modbus flowmeter or an analog flowmeter.
Hardware Used
- PLC: Micro820 (2080-LC20-20QBB)
- Slot 1: 2080-IF2
Inputs
Digital Inputs
| Input | Usage |
|---|---|
| 0 | Flowmeter Type (On = Modbus) |
Analog Inputs
| Input | Usage |
|---|---|
| 0 | 4-20mA Flowmeter |
| 1 | 4-20mA Pressure |
Outputs
Digital Outputs
| Output | Usage |
|---|---|
| 0 | Analog Flowmeter in use |
| 1 | Modbus Flowmeter in use |
Configuration
The system can be configured to use either an Analog Flowmeter or a Modbus Flowmeter. The system defaults to the Analog Flowmeter.
To enable the modbus flowmeter do one of the following:
- Jumper 24VDC to Digital Input 0
- Write 1/True to the tag “sw_UseModbusFlowmeter” from SCADA
To enable the analog flowmeter do BOTH of the following:
- Remove the 24VDC jumper from Digital Input 0
- Write 0/False to the tag “sw_UseModbusFlowmeter” from SCADA
When the system is configured to use the Analog Flowmeter, Digital Output 0 will be ON.
When the system is configured to use the Modbus Flowmeter, Digital Output 1 will be ON.
Customizing Modbus Parameters
The system defaults for modbus parameters enable communication with the Promag Modbus meters. The following tags can be modified to enable communication with different device types:
| Tag | Default | Usage |
|---|---|---|
| cfg_Flowmeter_ModbusNode | 1 | Node Address of Flowmeter |
| cfg_FlowRate_Register | 201 | Register of Flow Rate |
| cfg_FlowTotalizerA_Register | 203 | Register of Net Flow Total |
| cfg_FlowTotalizerB_Register | 205 | Register of Positive Flow Total |
| cfg_FlowTotalizerC_Register | 207 | Register of Negative Flow Rate |
| cfg_ResetTotalizerA_Coil | 104 | Coil to Reset Totalizer A |
| cfg_ResetTotalizerB_Coil | 105 | Coil to Reset Totalizer B |
| cfg_ResetTotalizerC_Coil | 106 | Coil to Reset Totalizer C |
| cfg_Status_Register | 1 | Register of Device Status |
| cfg_Units_Register | 61 | First Units Register |
The serial port is configured as a Master for Modbus RTU over RS485 with baud rate of 9600, 8N2.
SCADA Tags
The following tags would be relevant to read over SCADA:
| Tag | Type | Description | Access |
|---|---|---|---|
| cmd_ResetTotalizerA | BOOL | Reset Totalizer A | RW |
| cmd_ResetTotalizerB | BOOL | Reset Totalizer B | RW |
| cmd_ResetTotalizerC | BOOL | Reset Totalizer C | RW |
| Flow_EU_Max | REAL | EU Max Flow Scaling | RW |
| Flow_EU_Min | REAL | EU Min Flow Scaling | RW |
| Pressure_EU_Max | REAL | EU Max Pressure Scaling | RW |
| Pressure_EU_Min | REAL | EU Min Pressure Scaling | RW |
| cmd_ClearFlowTotal | BOOL | Clear analog Flow Total Command | RW |
| sw_UseModbusFlowmeter | BOOL | Use the modbus flowmeter | RW |
| use_ModbusFlowmeter | BOOL | Status of using Modbus Flowmeter | R |
| sts_FlowMeterModbusOK | BOOL | Flowmeter Modbus OK Status | R |
| val_Pressure | REAL | Pressure Reading | R |
| val_AI00_uA | REAL | uA Reading on AI00 | R |
| val_AI01_uA | REAL | uA Reading on AI01 | R |
| val_FlowRate | REAL | Flow Rate | R |
| val_FlowTotalizerA | REAL | Flow Totalizer A (Net Flow) | R |
| val_FlowTotalizerB | REAL | Flow Totalizer B (Fwd Flow) | R |
| val_FlowTotalizerC | REAL | Flow Totalizer C (Rev Flow) | R |
| val_FlowRate_Units | STRING | Flow Rate Units | R |
| val_FlowTotalizerA_Units | STRING | Flow Totalizer A Units | R |
| val_FlowTotalizerB_Units | STRING | Flow Totalizer B Units | R |
| val_FlowTotalizerC_Units | STRING | Flow Totalizer C Units | R |
| val_StatusString | STRING | FlowMeter Status | R |
Contributors
- Patrick McDonagh - Owner
- Ben Nabors - Collaborator