Post by testlogic on Sending Sequential Modbus TCP Packets ^{CODESYS Forge talk (Post)}
I have a Modbus TCP slave device where I need to do sequential writes to the same register. The register I'm writing to is kind of like a command line, each packet is a command word encoded in Hexadecimal. I am having difficulty implementing this system in CoDeSys 3.5 SP19. I feel like the structure of the program should be something along the lines of (Pseudocode): ModbusTCPSend(Command Register, Command1) ModbusTCPSend(Command Register, Command2) ModbusTCPSend(Command Register, Command3) I have tried to implement this with a rising edge trigger wMot1OPCode := 16#E1; //Stop Motor & Kill Program xMot1SendOP := TRUE; //Send OP on rising edge xMot1SendOP := FALSE; //Reset wMot1OPCode := 16#9E; //Disable Motor xMot1SendOP :=TRUE; //Send OP on rising edge xMot1SendOP := FALSE; //Reset Where "wMot1OPCode" is the IO map for writing to the command register, and "xMot1SendOP" is the rising edge trigger for that modbus channel. However, this doesn't work. The device never responds to the modbus commands. It seems like the trigger variable is switched too quickly for modbus to send the packet. I know the modbus register is working, because I can set the channel to cyclic and the device will respond. However, I can't use this reliably because I need each command to be sent once, in order. Cyclic keeps re-sending the commands and seems like it could miss a command as well if one was sent in-between cycle time. I have also trying using the Application trigger as described by https://faq.codesys.com/pages/viewpage.action?pageId=24510480, but this is also not working for me. See attached picture for my FBD code. This seems like a simple function, I can't tell what I'm doing wrong here. Thanks for the help.
Last updated: 2024-03-06

How to configure CODESYSControl_User.cfg in order to use a specific network card for OPCUA Server ^{CODESYS Forge talk (Thread)}
How to configure CODESYSControl_User.cfg in order to use a specific network card for OPCUA Server
Last updated: 2023-08-28

how to transfer raspberrypi runtime license from sdcard to dongle without the original raspi? ^{CODESYS Forge talk (Thread)}
how to transfer raspberrypi runtime license from sdcard to dongle without the original raspi?
Last updated: 2021-04-13

What is the best way to upgrade a project to a new version of Codesys? ^{CODESYS Forge talk (Thread)}
What is the best way to upgrade a project to a new version of Codesys?
Last updated: 2022-03-01

I want to use the function of PVT to realize move ^{CODESYS Forge talk (Thread)}
I want to use the function of PVT to realize move
Last updated: 2013-05-14

How to intercept a variation in the RetainPerstist variables (for saving to file) ^{CODESYS Forge talk (Thread)}
How to intercept a variation in the RetainPerstist variables (for saving to file)
Last updated: 2018-08-03

How to set "Always updatevariables" to "enable 2" by default in DeviceDescription. ^{CODESYS Forge talk (Thread)}
How to set "Always updatevariables" to "enable 2" by default in DeviceDescription.
Last updated: 2020-12-10

Specify Input Configuration "OnDialogClosed" Action to only react to certain Dialogs ^{CODESYS Forge talk (Thread)}
Specify Input Configuration "OnDialogClosed" Action to only react to certain Dialogs
Last updated: 2023-10-02

is it possible to connect to a newer runtime from HMI runtime 3.5.16 ^{CODESYS Forge talk (Thread)}
is it possible to connect to a newer runtime from HMI runtime 3.5.16
Last updated: 2024-07-02

The Ultimate Guide to Taxi Services in the UK: From Airports to City Travels ^{CODESYS Forge talk (Thread)}
The Ultimate Guide to Taxi Services in the UK: From Airports to City Travels
Last updated: 2024-08-08

Navigating the UK with Ease: Your Guide to Taxi Services from Major Cities to Key Destinations ^{CODESYS Forge talk (Thread)}
Navigating the UK with Ease: Your Guide to Taxi Services from Major Cities to Key Destinations
Last updated: 2024-08-08

how to extract the name of an FB to a variable ^{CODESYS Forge talk (Thread)}
how to extract the name of an FB to a variable
Last updated: 2024-10-01

Post by romrot on Trying to connect Codesys OPC server to Ignition ^{CODESYS Forge talk (Post)}
Trying to connect Codesys OPC server to Ignition, but I get this fault "java.lang.Exception: no anonymous token policy found"
Last updated: 2025-01-21

Unable to add EL6751 to Control RTE V3 on W11 IoT LTSC using Eng. V3.5 SP21 ^{CODESYS Forge talk (Thread)}
Unable to add EL6751 to Control RTE V3 on W11 IoT LTSC using Eng. V3.5 SP21
Last updated: 2025-09-08

Can't connect to my raspberry pi 3 after I tried to adjust CODESYScontrol.cfg ^{CODESYS Forge talk (Thread)}
Can't connect to my raspberry pi 3 after I tried to adjust CODESYScontrol.cfg
Last updated: 2021-06-17

How to connect Codesys Control win v3 to an ethercat device ^{CODESYS Forge talk (Thread)}
How to connect Codesys Control win v3 to an ethercat device
Last updated: 2021-04-26

How to generate PDO explicit request with RTR flag to TRUE ^{CODESYS Forge talk (Thread)}
How to generate PDO explicit request with RTR flag to TRUE
Last updated: 2018-06-13

Codesys closes instantly after I try to download to PLC ^{CODESYS Forge talk (Thread)}
Codesys closes instantly after I try to download to PLC
Last updated: 2022-12-21

Unable to get retain variables to work in a specific Raspberry Pi project ^{CODESYS Forge talk (Thread)}
Unable to get retain variables to work in a specific Raspberry Pi project
Last updated: 2019-12-03

Cannot convert type 'Unknown type: 'ADR(tabOrderIdArray)" to type 'POINTER TO ARRAY [0..0]OF INT' ^{CODESYS Forge talk (Thread)}
Cannot convert type 'Unknown type: 'ADR(tabOrderIdArray)" to type 'POINTER TO ARRAY [0..0]OF INT'
Last updated: 2021-04-26

what to do in case of a writing error to eeprom ^{CODESYS Forge talk (Thread)}
what to do in case of a writing error to eeprom
Last updated: 2020-11-26

Beaglebone Black - only one Ethernet port - how to connect to LAN, and EtherCAT? ^{CODESYS Forge talk (Thread)}
Beaglebone Black - only one Ethernet port - how to connect to LAN, and EtherCAT?
Last updated: 2022-01-16

Trying to Use Python Script to Exclude Certain Objects from Build ^{CODESYS Forge talk (Thread)}
Trying to Use Python Script to Exclude Certain Objects from Build
Last updated: 2019-08-20

Attempt to upgrade a pi 3 from a working V3.5.11 to V3.5.15 fails ^{CODESYS Forge talk (Thread)}
Attempt to upgrade a pi 3 from a working V3.5.11 to V3.5.15 fails
Last updated: 2021-07-13

Unable to connect to sensor even after Log says successful connection (Ethernet/IP) ^{CODESYS Forge talk (Thread)}
Unable to connect to sensor even after Log says successful connection (Ethernet/IP)
Last updated: 2022-06-29

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