Recent content by koen_verschueren

In my opinion there are 2 possible reasons. 1) Try command 3 (33624). Some slaves allow only "Read holding register (3)" for analog values while others allow "Read input registers (4)" and some allow both. 2) Modbus registers can be 0 or 1 based. This means an address in a slave can be...

Check following manuals. Modbus TCP is a Modbus RTU telegram (without CRC) in an Ethernet telegram. PI_MBUS_300.pdf gives a good description of all Modbus commands and command fields. http://www.modbus.org/docs/PI_MBUS_300.pdf...

Modbus RTU is a single master network. If you want to use multiple masters you will need a device capable of sharing slaves with multiple masters like the TSH series from ICP DAS. In this case you will need 3 TSH devices to connect the 4 masters to the slave. Possibly you can find other...

Modbus TCP to RTU gateway is a solution but the you need to change all masters to connect to the TCP side, slaves can stay on the RTU side. If the complete network is RTU, then it's better to share the slaves with as splitter like the TSH series from ICP DAS...

I suppose you have one Modbus TCP gateway and 10 serial Modbus RTU devices? If you use a Modbus TCP to RTU gateway like the: https://www.moxa.com/en/products/industrial-edge-connectivity/protocol-gateways/modbus-tcp-gateways/mgate-mb3180-mb3280-mb3480-series This gateway in it's most...

As mentioned by David it is not possible to have multiple masters on a modbus RTU network without a specialized module. You could use a module like the TSH series from ICP DAS. https://www.icpdas-usa.com/documents/WhitePaper-Multiple-Modbus-RTU-Masters-Sharing-One-Slave.pdf If Master1 and...

Yes you can but you need to filter the correct bytes on the receiving end. If you need byte 1 to 4, you will have to request register 1 up to register 3 (Modbus uses 16 bit registers). As a response you will get 6 bytes (0 to 5), filter out byte 1 to 4. You will need register 1 for byte 1 and...

Though it might work for some slaves there are slaves that will have problems with this approach. If you take a look at the modbus manual "http://modbus.org/docs/PI_MBUS_300.pdf" you will see modbus register are 16 bit registers. A request from the master requests a number of registers and...

Modbus is a register based communication protocol. Whether you are transmitting bits, bytes, words,... you are always transmitting a number of 16 bit registers. A single precision floating point uses 32 bits or 2 16-bit registers, a double precision floating point uses 64 bits or 4 16-bit...

Can you check the request and response? You can do this in Modscan by selecting 'Setup', 'Display options', 'Show Traffic'. Response should be according to manual http://modbus.org/docs/PI_MBUS_300.pdf If response is invalid, doublecheck baud rate, data bits, stop bits and/or swap wires...

I assume most applications let you query the meter and insert data in the DB in certain time intervals. See following links for your reference: http://www.aggsoft.com/serial-data-logger/tutorials/modbus-tcp-power-meter-data-logging.htm...

1- There are a lot of programs you can use to read and/or write Modbus data p.e. SCADA, HMI, Modbus to Excel, Modbus to database, Modbus scanners. It all depends on what you want to do. Start with a free Modbus Scanner p.e. Modscan from WinTech just to get acquainted with the Modbus protocol...

If you suspect an infected powermeter transfers a virus to your PC over the serial line using Modbus, I think you have to fire your programmer or use software on your PC from a reliable supplier. If you are really in control over the master communication on the PC the risk is not existing...

With all bus connections there is always a possibility one device infects an other, but in this case i believe the risk is as good as impossible. Power meters in general do have a microcontroller, but they are not PC's with operating systems vulnerable to viruses. Modbus is a master slave...

In the S5-1500 you will have to use MB-CLIENT or MB-SERVER function depending on who will be server or client.