Steve Bailey
Lifetime Supporting Member + Moderator
I received the following by PM from Misel00. I don't do private consultations without a purchase order, so I'm reposting here as it may be of general interest.
I'm working currently on a Modbus TCP application with a GE Quickpanel, and haven't been able to find how to read the current state of communications with a device connected via ethernet and using the Modicon tcp/ip driver.
I'm guessing there is a specific internal variable that monitors this communications, but cannot find any references on this. I would appreciate if you could guide on this, since it's the missing point to finish a project I'm working on.
There is no system bit or word in a Quick Panel that gives information about the state of any of the device communications drivers. If you need one, you'll have to roll your own. There are many ways to handle it. If the Modbus slave has a clock variable that changes regularly, you could monitor that and failure to change within a reasonable amount of time is an indicate of a communications fault.
If you have the ability to program the Modbus slave, you could add a "handshake" bit monitored by the Quick Panel. Have the Modbus slave turn the bit on whenever it detects that it is off and the Quick Panel turn the bit off whenever it detects that it is on. On the Quick Panel side, if it remains off for too long, you have a communications fault. On the Modbus side, if the bit remains on too long the Modbus device knows there is a problem.
I'm working currently on a Modbus TCP application with a GE Quickpanel, and haven't been able to find how to read the current state of communications with a device connected via ethernet and using the Modicon tcp/ip driver.
I'm guessing there is a specific internal variable that monitors this communications, but cannot find any references on this. I would appreciate if you could guide on this, since it's the missing point to finish a project I'm working on.
There is no system bit or word in a Quick Panel that gives information about the state of any of the device communications drivers. If you need one, you'll have to roll your own. There are many ways to handle it. If the Modbus slave has a clock variable that changes regularly, you could monitor that and failure to change within a reasonable amount of time is an indicate of a communications fault.
If you have the ability to program the Modbus slave, you could add a "handshake" bit monitored by the Quick Panel. Have the Modbus slave turn the bit on whenever it detects that it is off and the Quick Panel turn the bit off whenever it detects that it is on. On the Quick Panel side, if it remains off for too long, you have a communications fault. On the Modbus side, if the bit remains on too long the Modbus device knows there is a problem.
