ModMAG® Electromagnetic Flow Meters
M-Series® | B-MAG Electromagnetic Flow Meters
M2000 Modbus RTU Communication Daughterboard
OVERVIEW
The Modbus RTU Communication daughterboard expands the connectivity of the M2000 flow meter by facilitating communication over RS485 using the Modbus RTU protocol. The RS485 allows for greater communication distances than RS232 and provides for multi-point networking.
External Connections (Pins 31 – 39)
A diagram shows a horizontal row of 9 rectangular blocks, labeled sequentially from left to right: 39, 38, 37, 36, 35, 34, 33, 32, 31. The title above this row is 'External Connections (Pins 31 – 39)'.
J4 RS485 / RS232 Mode Selection Jumper
A diagram illustrates jumper J4, labeled 'RS485 / RS232 Mode Selection Jumper'. It shows three pins. Pin 1 is connected to RS485. Pin 2 is connected to RS232. The jumper selects between these two modes.
J3 120 Ω Termination Jumper
A diagram illustrates jumper J3, labeled '120 Ω Termination Jumper'. It shows three pins. Pin 1 is connected to a 120 Ω termination. The jumper can be set for '120 Ω' or 'No Termination'.
A 11-pin plug is shown, labeled: "Connect to 'COMMUNICATION' plug on Amplifier Board".
Pinout Description
| Pin No. | Pin Name | Description |
|---|---|---|
| 31 | Analog Output | 0...20 mA, 0...10 mA, 2...10 mA, 4...20 mA |
| 32 | COM | Common ground connection |
| 33 | RS232 RX | Receive input for RS232 |
| 34 | RS232 TX | Transient output for RS232 |
| 35 | COM | Common ground connection |
| 36 | RS485 (-) | Inverting signal for RS485 |
| 37 | RS485 (+) | Non-inverting signal for RS485 |
| 38 | RS232/485 Shield | Shield input for RS232 or RS485 |
| 39 | Chassis | Connection for coupling shield to chassis |
INSTALLING THE DAUGHTERBOARD
- Use the provided self-adhesive tape to secure the foam pad near the 11-pin COMMUNICATION connector.
- Remove the board support screw near the 11-pin COMMUNICATION connector to install the green chassis connection wire (with an eye washer). Connect the other end of the chassis connection wire to pin 39.
- Select operation mode RS485 or RS232 for the daughterboard using J4.
- For RS485 mode only: Select the termination (that is, 120 Ω or No termination) using J3.
? NOTE: 120 Ω termination is typically required when the meter is the first or last device in the communication link.
? NOTE: It is assumed all signal biasing is accomplished at the Modbus RTU master node. For biasing calculations, receiver input impedance is 96 kΩ or 1/8 unit loads.
⚠️ CAUTION: DISCONNECT THE INPUT POWER BEFORE ACCESSING THE EQUIPMENT.
- Turn off the meter and insert the daughterboard into the keyed 11-pin COMMUNICATION connector on the amplifier.
CONFIGURING PORT B MODBUS RTU
The Modbus RTU Communication Daughterboard is a slave device that communicates over Port B. The following Port B settings are configurable from the meter's menu manager.
| Setting | Options |
|---|---|
| Port address | 1 to 247 |
| Ext. port address | Not applicable for Modbus RTU daughterboard |
| Baud rate | 9600 (default), 19200, 38400 |
| Data bits | 5, 7, 8 (default) |
| Parity | None, Even (default), Odd |
| Stop bits | 1 (default), 2 |
To change the configuration of Port B to match your system requirements:
- Turn on the meter.
- Navigate to Main Menu > Communication > Port B Settings.
- Verify that the settings are an appropriate match for the application. If not, change the settings as necessary.
Please refer to the M2000 Modbus Memory Map Application Brief for accessible registers.
