RKI Instruments M2 Series - Manual (Page 58)

53 M2 Transmitter Operator’s Manual
Using the M2 in a 4-wire Modbus System
Although the M2 is a 2-wire Modbus RTU device, it can be used with a 4-wire Modbus
controller if the system wiring is modified as follows:
• Connect the controller’s TxD0 and RxD0 wires together and use this connection as the
2-wire Modbus D0 signal.
• Connect the controller’s TxD1 and RxD1 wires together and use this connection as the
2-wire Modbus D1 signal.
• Connect these D0 and D1 signals and the common wire from the controller to the 2-
wire Modbus Network of M2s.
Modbus Mode
Modbus Mode allows you to configure various parameters relating to the Modbus setup
of the M2. Modbus Mode includes a 5-minute time-out feature. If you do not press a
control button for 5 minutes, the M2 automatically returns to normal operation.
NOTE: If the M2 returns to normal operation because of a time-out, it enters a warm-
up period just as it does when it is first turned on.
1. While in normal operation, simultaneously press and hold the DOWN/NO and
ENTER buttons for 5 seconds to enter Modbus Mode. Release the buttons when the
following screen appears.
2. To exit Modbus Mode, press and release the DOWN/NO button. The M2 will return
to normal operation.
To continue in Modbus Mode, press and release the UP/YES button. The current
ENABLED/DISABLED setting will appear.
3. If you want to change the currently displayed parameter, use the UP/YES and
DOWN/NO buttons to adjust it to the desired setting, then press ENTER to continue
to the next parameter.
If the currently displayed parameter setting is OK, press the ENTER button to proceed
to the next parameter.
Table 11 lists the M2 Modbus Mode parameters you can set. Table 11 also lists the
factory set value for each parameter.
Set Up
Modbus?