LoggerV serial and CAN ports

Scope

The LoggerV has six isolated communication ports for devices: two RS232 ports, two RS485 ports and two CAN bus ports.

RS232 port: one 3-pin connector.
RS485 port and CAN bus port: two RJ45 sockets. Connect more than one device to a port without a splitter.

This article is for installers. It gives the port names, the cable connections and the port settings. To add a device to a port, see How to add a device in myPower24.

This port set is on the standard LoggerV, for example hardware version 221.

Ports

RS232 - 1: RS232 port 1, name rs232-1 in the Add Device wizard.
RS232 - 2: RS232 port 2, name rs232-2.
RS485 - 1: RS485 port 1, name rs485-1.
RS485 - 2: RS485 port 2, name rs485-2.
CANBUS 1: CAN bus port 1, name can-1.
CANBUS 2: CAN bus port 2, name can-2.

Each port has electrical isolation. The Actual Values tab of the LoggerV shows the number of each port type in the Com Interfaces section: RS232 Isolated Ports, RS485 Isolated Ports and CANBUS Isolated Ports.

Two RJ45 Sockets

The RS485 ports and the CAN bus ports have two RJ45 sockets each. The LoggerV thus has four RS485 sockets and four CAN bus sockets. The two sockets of one port connect to the same bus.

RS485 port: connect more than one device to the same bus. Each device on the bus must have a different Modbus address.
CAN bus port: connect more than one device to the same bus. All devices on the bus must use the same bus speed.

An RS232 port has one 3-pin connector. Connect one device to each RS232 port.

Wiring

The Add Device wizard shows the connection diagrams. See How to add a device in myPower24.

RS232 connector: pin 1 is RX, pin 2 is TX, pin 3 is GND.
RS485 RJ45 socket: pin 4 is B (+), pin 5 is A (-), pin 1 is ground. The ground connection is optional.
CAN bus RJ45 socket: pin 4 is CAN high, pin 5 is CAN low.
Cable: a standard CAT network cable with RJ45 plugs.
Cable length: the maximum length decreases when the bitrate increases, as on all RS485 and CAN bus cables.

Termination

These termination rules apply to the RS485 bus and to the CAN bus. A termination is a 120 Ω resistor between the two bus wires. It stops signal reflections at the end of the cable.

The LoggerV has no internal termination resistor on its RS485 and CAN bus ports. RJ45 termination plugs come with the LoggerV.

Termination plug: an RJ45 plug with a 120 Ω resistor in it, under a black plastic cover.
Termination points: the two ends of the bus, and no other point.
LoggerV at one end of the bus: put a termination plug in the free socket of the port.
LoggerV in the middle of the bus: use the two sockets for the bus cables. Do not install a termination plug.
Last device on the bus: use the termination switch or the termination resistor of the device. If the device has no termination, connect a 120 Ω resistor between the two bus wires.
Bus wires: A and B on an RS485 bus, CAN high and CAN low on a CAN bus.
Battery system with more modules: some battery systems have a termination switch on each module. Set the termination on the last module only. Read the battery manual.

Too many terminations load the bus, and the devices then do not receive the signal correctly.

Install a termination plug when the LoggerV is at one end of the bus. Without termination, signal reflections cause communication errors.

Termination Check

Measure the resistance of the bus to make sure that the termination is correct.

Remove the power from all devices on the bus.
Measure the resistance between the two bus wires at one device.
Compare the value with the list below.

60 Ω: correct. There is a termination at each end.
120 Ω: one termination is missing.
40 Ω or less: there are too many terminations.
Very high (open circuit): there is no termination, or the cable is broken.

A device with a fixed internal termination changes the result. Refer to the device manual.

Serial Port Settings

The settings of an RS232 or RS485 port apply to all devices on that port. All devices on one serial port must use the same settings.

The LoggerV uses Modbus RTU on the RS232 and RS485 ports. For how Modbus operates and what the Modbus errors mean, see Modbus RTU and TCP.

In the Add Device wizard, go to the Interface Selection step.
On the port card, click the gear.
Set the values:
- Baud Rate: 2400, 4800, 9600, 19200, 38400, 57600, 115200 or 230400.
- Data Bits: the number of data bits.
- Stop Bits: the number of stop bits.
- Parity: NONE, ODD or EVEN.
Click Change.
Wait for the message Serial Config successfully changed.

The port card then shows the new Baud Rate, Data Bits, Stop Bits and Parity.

Examine all devices on a serial port before you change the port settings. A device that uses different settings stops communication.

CAN Bus Speed

You cannot set the bus speed of a CAN bus port. The device driver of the first device on the port sets the bus speed. The port card in the Add Device wizard shows the Bus Speed in kbps.

Available speeds: 125, 250, 500 and 1000 kbit/s.
Port with no device: the port is disabled. The port starts when you add a device to it.
Two devices with different speeds: the port uses the speed of the first device. The second device does not communicate. Connect the second device to the other CAN bus port.

Port Status

The Interfaces tab of the LoggerV shows one section for each port. Each section shows the devices on the port in Enabled devices and the live values in INTERFACE STATISTIC.

For a serial port:

Interface Status: the port status.
Bitrate: the baud rate, in b/s.
Settings: the data bits, parity and stop bits.
Transmit Speed, Received Speed: the data rate now, in bit/s.
Total Utilization: the port load, in %.
Transmit Bytess, Received Bytess: the total data, in kbyte.
Error Frames: the number of frames with an error.

For a CAN bus port:

Interface Status: the port status.
Line Status: the bus status.
Bitrate: the bus speed, in kbit/s.
Tx / Rx Rate: the data rate now, in kbit/s.
Bus Load: the bus load, in %.
Total Transmit Frames, Total Received Frames: the total number of frames.
Rx/Tx Error Counter: the number of errors.

Click Reset Statistic to set the CAN bus counters to zero.

Permissions

Viewer: can see the ports and the port status. Cannot add a device to a port.
Editor, Installer, Full control: can add a device to a port.
Serial port settings: the platform does not check the access level. All users who can open the LoggerV page can change the serial port settings.

Troubleshooting

No CANBUS interface detected: the LoggerV has no CAN bus port, or the port did not start. Make sure that the LoggerV hardware has CAN bus ports. The same message shows for the other port types.
Search for device Fail!: the scan did not find the device. Examine the Modbus address, the serial port settings and the wiring.
Timeout: the LoggerV did not reply to the settings change. Examine the logger connection, then try again.
A CAN bus device does not communicate: another device on the same port uses a different bus speed. Compare the Bitrate on the Interfaces tab with the speed of the device.
Error Frames increase on a serial port: the baud rate, the parity or the wiring is not correct.