Nematron touch screen

[javajoe]

I am working with a Nematron MT8070iH touch screen HMI.  I have set the PLC up as MODBUS ASCII with RS-232 communication (38400,N,8,1).  I am able to read output status from the plc but cannot write to Inputs.

If I understand correctly, no special configuration needs to be done in my code on the PLC for MODBUS communication.  And since I seem to be able to read outputs with a MODBUS address from the HMI it looks like I am correct in that thought process.

I am not sure what is going on.  I have tried different timeout settings on the HMI with no luck.

Any help will be appriciated.

[support]

When you write to an input in the PLC, it will be changed for one scan time only and after that the PLC I/O scan routine will update it with the actual logic state of the physical I/O. You cannot force an input to stay permanently on or off. However, for input that require only a momentary one you can still force it and it will execute the logic only once.

If you need to permanently turn on an input condition, use an internal relay instead and use that internal relay in parallel to the physical input for your control.

[javajoe]

Thank you for the help with the input condition.  

I am now having trouble reading data from the PLC using the MODBUS protocol.  I have tried setting a numeric display that is populated by a direct call to the MODBUS address as well as using a macro to get the data and then populate the display with no luck on either attempt.

[support]

Did you run the SETPROTOCOL command in the PLC? Or did you change the PLC's baud rate settings using SETBAUD command? Both the HMI and the PLC must be set to the same baud rate, data bit, stop bit and parity configuration.

If you run the SETPROTOCOL make sure that it is set to the same protocol as your HMI. Modbus ASCII and Modbus RTU are very different and if you set it to one type of protocol it will not be able communicate properly.

[javajoe]

Did you run the SETPROTOCOL command in the PLC? Or did you change the PLC's baud rate settings using SETBAUD command? Both the HMI and the PLC must be set to the same baud rate, data bit, stop bit and parity configuration.

Yes SETPROTOCOL is used but it is set to 0 (auto sensing) and SETBAUD = 6 (38400).  The HMI is transmitting MODBUS ASCII, @ 38400 BAUD.

If you run the SETPROTOCOL make sure that it is set to the same protocol as your HMI. Modbus ASCII and Modbus RTU are very different and if you set it to one type of protocol it will not be able communicate properly.

I am able to use Lamp displays and watch relays and outputs fire, but can not get anything from timers, counter, or DMs.

[support]

If you are able to control the output lamp via modbus protocol it means you do have communication. You said you can't read the timers, counters and DMs. Are you trying to read timers and counters set value or present value? Set value is not directly mapped to Modbus space. Present values are mapped but will only show up when the timers and counters are working (not reset state).

DMs are mapped to 41001 (1 offset, in decimal) onwards. Make sure that you have mapped to the correct address.  If your device is using zero offset hexadecimal you have to convert correctly.

[garysdickinson]

SPAM

[support]

SPAM

Yes, we saw it and have deleted the offending spam post. The new member who did the spamming was also deleted from the forum. But these spammers will keep coming back. Not sure if it was a robot or a human doing the spamming. Maybe the robot is now sophisticated enough to break the word challenge barrier and if so that's bad news for many websites and forums.

[garysdickinson]

The robots are a lot smarter than I am.

I tried to report the spam using the "Report to Moderator", but was unable to enter the correct words for the graphics challenge on 3 attempts.

That's why I'm using the "Reply" mechanism on the forum

Gary D

[support]

Thanks for your attempt to report the SPAM to us. We appreciate it.

Yeah I agree the word challenge is getting more difficult. Sometime we ourselves have trouble deciphering the words as well and that have led to some unhappiness among users. Unfortunately we don't have much control over it since we are just "borrowing" the word challenge hosted by http://www.captcha.net. Probably www.captcha.net is upping the ante to fight the spamming robots which are getting smarter. Perhaps soon another way need to be invented to battle with the spamming robot.