To change the charging algorithm from the menu system:
1. From the DXM Modbus Slave LCD menu, navigate to System Config > I/O Board > Charger.
2. Select Solar for solar panel configurations.
To change the charging algorithm by writing to Modbus register 6071 on the I/O base board (Slave ID 11):
1. Write a 0 to select the solar power charging algorithm.
Modbus Slave ID
Modbus Register
Description
11 *
6071
Battery backup charging algorithm.
0 = Battery is recharged from a solar panel
1 = Battery is recharged from 12 to 30 V dc (default)
The following power operating characteristics are stored in Modbus registers.
Battery voltage
If no battery is present, the value in this register is less than 5 V. If the value in this register is greater than the
incoming voltage register, the battery is powering the system.
Battery charging current
The charging algorithm charges the battery when the incoming voltage register value is greater than the battery
voltage register value. This registers shows the charging current in milliamps.
Incoming supply voltage
The incoming power can be from a solar panel or from a power supply. The battery is charging when the incoming
voltage register value is greater than the battery voltage register value. The battery is powering the system when
the incoming voltage register value is less than the battery voltage register value.
On-board thermistor temperature
This register stores the on-board thermistor reading in tenths of degrees C, this is not a calibrated input: divide by
10 to calculate the temperature in degrees C. For calibrated temperature inputs, define one of the universal inputs
as a temperature input.
Modbus Slave ID
Modbus Register
Description
11 *
6081
Battery voltage (mV)
6082
Battery charging current (mA)
6083
Incoming supply voltage (mV) (solar or power supply)
6084
On-board thermistor temperature (
⁰
C)
* The Slave ID for the base board is set at the factory. This may be changed using the base board DIP switch settings.
4.2.2 Connecting a Battery to the
DXM Modbus Slave
When attaching a battery to the DXM Modbus Slave as a backup battery or as a solar battery, verify the charging algorithm
is set properly. The factory default setting for the battery charging algorithm assumes you are using 12 to 30 V dc to
recharge the battery.
The charging algorithm is designed to work with a sealed lead acid (SLA) battery only.
• When using 12 to 30 V dc, connect the 12 to 30 V dc + to pin 2 and connect the ground to pin 3.
• When using main dc power with a back up battery (default configuration), connect the incoming main power pin 2
(+) and to pin 3 (-). Connect the 12 V sealed lead acid battery to pin 4 (+) and pin 5 (-). The incoming main power
must be 15 to 30 V dc to charge the battery.
• When using a solar panel, connect the solar panel output to pin 2 and connect the ground to pin 3. Connect the 12
V dc SLA battery to pin 4 (+) and pin 5 (-). To change the charging algorithm, refer to
Supplying Power from a Solar
Panel
on page 10.
The battery charging algorithm defaults to a battery backup configuration. To charge the battery from a solar panel, change
the battery charging algorithm.
1. From the DXM Modbus Slave LCD menu navigate to Setting Config > I/O Board > Charger.
2. Select Solar for solar panel configurations or DC for battery backup configurations.
DXM150-Sx Wireless Modbus Slave
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