In short
- In closed loop, the battery sends its limits and charge level to the inverter over CAN or RS485.
- Only the master battery talks to the inverter; the others report to it through the link cables.
- Most communication faults come from the cable pinout, the wrong port, the protocol setting or the master address.
Closed-loop communication means the battery management system sends live data to the inverter: state of charge, maximum charge and discharge current, charge voltage, alarms. The inverter follows those values instead of guessing from voltage alone.
CAN or RS485
Most hybrid inverters talk to Pytes batteries over CAN, some over RS485. The battery has separate sockets for each, and the inverter expects one of them. Plugging the right cable into the wrong socket is the most common mistake on a new install.
The cable is not a network cable
Battery communication cables use RJ45 plugs, but the pins used for CAN or RS485 differ between brands. A standard Ethernet cable may work for one inverter and not for another. Use the cable supplied for your inverter, or check the pinout in both manuals.
Master battery and addresses
With several batteries in parallel, one acts as master and talks to the inverter. The others connect to it through link cables and report their state. The address or DIP switch setting decides which one is master. A wrong address usually shows as a communication alarm or as only one battery appearing.
Protocol on the inverter
The inverter must be set to the battery type or protocol that matches Pytes. Many inverters list it by brand. If the inverter is set to a generic lead-acid or user mode, it will ignore the battery data even when the cable is right.
Reading the batteries without touching the loop
Pytes Monitor connects to a free communication port and reads each battery, its cells, temperatures and alarms. It does not join the closed loop and sends nothing to the inverter, so you can watch what the batteries report while the link with the inverter stays as it is.
Common questions
Can Pytes Monitor replace the communication cable to my inverter?
No. It uses a separate free port and only reads. The inverter keeps its own link with the master battery.
Do I need closed loop at all?
It is not mandatory with every inverter, but it gives better charge control and accurate state of charge. Most installers use it when the inverter supports it.
How do I know which battery is master?
The address or DIP switch setting decides it. Your battery manual shows the setting for a single battery and for a parallel bank.
