RKI Instruments M2 Rig Monitor - Manual (Page 41)

M2 Rig Monitor Operator’s Manual 36
Figure 14: Multiple M2 Rig Monitors in a Two Branch Configuration
Using the M2 Rig Monitor in a 4-wire
Modbus System
Although the Rig Monitor 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 Rig Monitors.
Modbus Mode
Modbus Mode allows you to configure various parameters relating to the Modbus setup
of the Rig Monitor. Modbus Mode includes a 5-minute time-out feature. If you do not
press a control button for 5 minutes, the Rig Monitor automatically returns to normal
operation.
NOTE: If the M2 Rig Monitor 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
Modbus
Master
M2
Termination
Jumper
Installed
M2
Termination
Jumper
Not Installed
M2
Termination
Jumper
Not Installed
M2
Termination
Jumper
Not Installed
M2
Termination
Jumper
Not Installed
ID = 1
ID = 2 ID = 3 ID = 4
M2
Termination
Jumper
Installed
ID = 128
ID = 127
Up to 128 M2s can be connected without a repeater.
RS-485 RS-485