Configure BMS to update system SoC to a CCGX using MODBUS-TCP (superseded)

This is a superseded interface approach not applicable to new installations. All new system installations should normally be installed using a CANBus connection to the Victron Energy CCGX/Venus GX system and should use DVCC for much enhanced outcomes - as documented in other guide articles.

You can add an external USB-to-CANBus dongle to any original (non-CANBus) BMS model to enable CANBus interfacing on that older hardware, which then works exactly as for the latest BMS model in terms of CANBus connection and interface. This is also explained in other guide articles.

If for some reason none of that is applicable to your situation, then this (older) method to update SoC (only) using MODBUS-TCP does still work. However it offers no active charge/discharge control from the BMS to the GX - it merely updates the SoC value shown by the GX. 

Prerequisites:

• The IP address of the GX must be static/fixed - you need to either manually lock in an IP address on the CCGX, or ensure that your DHCP server is providing a static (consistent) IP address each time the CCGX boots. If you don't do this, the updates will stop working any time that the CCGX reboots and obtains a different IP address. 
• If this SoC update approach is used, the maximum system charging voltage configured into all Victron charging elements (AC and DC) should be 56.5 Volts or lower. This ensures that there will not be unacceptably high voltage spikes generated by charging devices, in the absence of CANBus-controlled charge and discharge current and voltage control. 

Here are the steps to configure and enable this approach to update GX SoC:

Enable MODBUS-TCP is enabled in the CCGX 'Services' menu:

Select the Multi/Quattro device on VE.Bus as the "Battery Monitor" information source:

Ensure the Multi/Quattro will accept the MODBUS-TOC SoC updates from the BMS

Using VE.Configure, you must ensure the ‘battery monitor’ function is ON, in the 'General tab', as per the example page below.

The battery capacity value should be set correctly (200Ah per ZBM2/ZCell). The other battery monitor fields are non-critical and don't need to be changed.

(The battery monitor is the path by which the MODBUS-TCP updates work - it must be enabled, and then the regular MODBUS-TCP updates from the BMS update the SoC from that monitor so that it is correct. These updated SoC values are then read back in to the CCGX and used as the SoC for the running system).

Enable sending of SoC updates from the BMS to the CCGX

Create a MODBUS-TCP endpoint via the BMS Configuration->Digital I/O menu and the 'Endpoints' tab for SoC update.

The IP address you enter should be the correct one for the CCGX in your local system.

The other values should be as shown below - be careful to set the Unit Number, Register Number and Register Type correctly.

IMPORTANT: You must use the 'Save' button after entering the information on the Periodic entry below or the changes you make will not be saved.

Create an (optional) MODBUS-TCP endpoint to control AC PV output when off-grid

This second MODBUS-TCP endpoint can enable/disable any AC PV attached to the output side of the Victron inverter/charger when necessary (using frequency shifting), to avoid the potential for overloading the energy system and causing an AC system shutdown when all ZCell units are full or otherwise unable to accept further charge. 

This optional endpoint only works when the system is running off-grid (no grid connection or grid connection has failed). 

Again, be careful to make all the fields correct as per the below - unit number, register, etc, if you install this optional endpoint:

Create Periodic update rule(s) in the BMS

Now create "Periodic" update rule(s) to send the State of Charge value and the AC PV Disable signal from the BMS to the CCGX via the endpoints you have just created. 

The update rate you choose for these periodic update functions is not critical -  10-20 seconds is generally fine. 

If you just want to update SoC, put in just the SoC rule; You don't need to add the AC PV control rule if you have not decided to create the AC PV control endpoint. 

Be sure to press 'Save' at the end of each line after you enter the line in, or it will not take effect.

Activate your changes in the BMS

Finally, restart the BMS and activate your changes using the "Apply Changes" tab and selecting 'Restart'.

Your changes will not take effect until you do this:

 

It will take about one minute after "Apply Changes" is selected, before the BMS will commence updating information to the CCGX - be patient. 

If the SoC on the CCGX does not update after a couple of minutes, you can try using the Tools->DIO Endpoint Tool to manually set SoC values and see if they appear on the CCGX. 

If you get an error back from the BMS when you try to manually set the value, it is likely that you have not enabled MODBUS-TCP on the CCGX or that there is a problem with the TCP/IP network connection between the BMS and the CCGX.

About the AV PV Disable function

The AC PV Disable command triggers shutdown of the AC PV Inverter using AC Frequency shifting signals to the PV inverter(s) attached to the system.

The AC PV Disable outcome will not be functional except when the Multi/Quattro is running in invert mode with no upstream AC connected (e.g. off grid or on-grid but during grid failure). The system cannot frequency-shift if it is synchronised to an operative upstream AC energy source.

It also requires that either the "ESS Assistant" or the  "PV Support Assistant" is loaded into the inverter (these assistants are what actually implement the frequency-shift cutoff when needed)

If you don't understand what this means or you don't think you need this, then... you probably don't need this!