[Weird modbus TCP/IP behavior on one of my PLCs (V700)]

What I do is a kind of whatchdog: master writes continously 1 to an register (MI10); slaves resets it.

In the example, I use T50 to detect comms lost with master and act acordingly.

 

[Modbus problem]

I would  check: 

1. Terminal resistors, only at the ends of the network.

2.  Comms parameters, baud and so on.

3. Register numbers.

4. Delay time between readings of each slave.

 

[I can't send a simple email through my panel]

Set DNS provided by your ISP.

If PLC is connected to the same network of your computer, then verify its DNS server in network connection details of Windows control panel

[V570 PLC + HMI]

20 hours ago, engineer118 said:

Is there a way to do this through visilogic? Unfortunately the HMI screen is completely black so there is no possibility of navigating to INFO mode from the HMI (Information Mode (unitronicsplc.com))

I´m affraid no. As long as I remember, INFO mode is not accesible via remote operator neither remote access, so, you would be completely blind to perform SD actions from INFO mode.

 

I would get a new unit, exchange CPU as Kratmel suggested then verify if project is burnt.

[V570 PLC + HMI]

Another option: use SD memory card and attempt  CLONE ALL from INFO mode, so you can move program, OS, data, datatables to a new unit.

I don´t remember if SD Password must be enable on ladder to be able to use this option.

[Web Service - Web page occasionally shuts off]

You can reconfigure the socket periodically, let´s say, every 5 minutes. This was my workaround some time ago.

[Trying to get infos from a Voltmeter connected to a MODBUS]

I suggest to double check wiring, network configuration (ID, baud and so on) on the meter side and register numbering, response timeout.

Also, first try using a Modbus software.

Any chance that 5000 is hex?  If so, set decimal address.

[Connecting more than one modbus slave over Panel Ethernet]

It´s a normal behavior.

If you want your PLC act as slave (named server in Modbus TCP), you configure it under PLC Communications | Protocols | MODBUS | Slaves, either Ethernet or RS485. Then, it will be another slave in the network.

If you want your PLC act as a master (named client in Modbus TCP), you must configure all your slaves under PLC Communications | Protocols | MODBUS | Masters, either Ethernet or RS485. Then, it will be the master in the network. All slaves must have unique IP (Ethernet) or ID (RS485).

 

 

 

[Modbus slave trigger in Visilogic]

I would use two different MB, one for local control and another for Modbus commands. In ladder, use one or another based on your requirements (Modbus control enabled - remote control - or local control).

In Vision family once you enable Modbus as a slave, you cannot restrict access to only desired operands, all of them can be read/writen using proper addresses.

[Thermal image]

11 hours ago, Flex727 said:

I'd love to know what SI 14 is telling you, though you would need to calculate it using SB 14 in ladder first.

I like to have a screen on most of my projects that includes PLC temperature, scan time, and other misc info that could be useful for troubleshooting.

I´ve used it and not always gives too much information about how hot is the snap.

[How can i remove/ identify this error "Value is not available because the limit for function tags was reached""]

Here you are using AV_001 as direct coil, it must be direct contact:

 

IP address is missing for remote slave1:

 

PLC is acting as Modbus TCP server or client? You set both modes up.

 

Active bits are missing in coils periodic task.

 

[Question about using unitronics PLC as Modbus TCP Master/Slave]

Mod add, pinned in "topics almost worth pinning"

1. Initialize the socket as usual, but using UDP instead TCP.

2. Configure Modbus TCP.

3.  Execute Modbus function. There is not need to open socket nor wait for open connection.  What I do here is to increase a pointer to read sequencialy all slaves.

4. Wait for response and process your data.

 

On 5/6/2022 at 11:30 PM, Flex727 said:

 Are there any issues with mixing UDP and TCP on the same network? What are the disadvantages to using UDP vs. TCP?

I´ve used up to 4 sockets mixing TCP, UPD and TCP_Raw with no problems at all. Keep in mind that each socket acts as a logical port, so you may use each one with its own port number and protocol.

UDP disadvantages:

1. Packages lost because of inherent lack of error check of UDP, but it´s compensated with more speed and less comms overhead. 

2. Some devices only accept TCP connections.

 

 

[Action performed once per week]

¿have you tried DAY OF WEEK function?

[Question about using unitronics PLC as Modbus TCP Master/Slave]

What I do is to use UDP instead of TCP (for the socket using Modbus). That way, there´s not need to open/close connection each time you need to communicate to the next slave.

Be aware that some devices only accept TCP

[How can i remove/ identify this error "Value is not available because the limit for function tags was reached""]

I think you misundesrtood the custom controls use. 

You create a single custom control to all valves, other to all pumps, that share the same frame, buttons and layout.  Then, you place the control on the screen (or screens) you need it and set parameters associated with the device (pump, valve, ...) you want to operate.

[Modbus RTU doing things that should not be possible [SOLVED]]

Some suggestions:

1. Check the termination resistors.

2.  Change aperiodic for periodic readings. You can either control single slave readings with Active bit.

3. Use minimum response time.

4. Take a look to "Dropped Operations" information in help file. It may help to solve your issue.

 

[Need help with ladder logic algorithm]

See attached file.

It gives you an idea.

 

DCHG_ORDER.vlp

[SAMBA 43 J R20 CANbus not initializing]

8 hours ago, Sergio Ramos said:

So I would have to wire in two power sources? In the CANbus pins and the HMI Pins? 

No, just one device on the entire CANBus network. You can use same PS used to power PLC, however I recommend to protect with fuse the CANBus power lines.

8 hours ago, Sergio Ramos said:

Wouldn't adding an external PS make my code a bit irrelevant since it would start the communication immediately without user input? Is there a solution for this?

Is your code what defines when and how exchange data, you may add conditions as required.

8 hours ago, Sergio Ramos said:

Would I have to buy an expansion module to be able to power the CANbus ports?

I don´t think

 

 

[SAMBA 43 J R20 CANbus not initializing]

You should use an external PS wired to +V - V

[data table using string]

You need to reserve 5 MIs for each program name, e.g. name of program 6 use MI33 up to MI37, program name 7 use MI38 up to MI42 and so on. Also make sure set MB55 if you watn to update name to be updated on screen. I use to SET that MB continously in my ladder.

 

[Modbus TCP Socket doesn't close, when I turn "Off" the Active Periodic bit.]

I would use one UniStream as a master, reading from your temperature slave and then writing its value to others Unistream acting as slave as well.

[HMI hangs on splash screen - Samba 43]

Check timer T3 preset, it could be somehow being set to 0 then would nevr load "2. Main" screen.

It can be modified from INFO mode

[TE Timer failure]

I would INC MIs in another net using positive transition of timers. 

[Visilogic Keypad Disappears on v570]

check if load screen is used with transition contact

[Numeric box dynamic color]

@Cara Bereck Levy as it is not currently available, I suggest to implement it in next versions.