mani.sarathy
Member
- Join Date
- Aug 2002
- Posts
- 5
I am having trouble in getting a VersaMax Micro PLC to communicate with a custom designed Operator Interface-via the
Port 1(The Port with an RJ45 Connector).I have set the communication parameters to the default-19200BPS,Pqrity-Odd,Stop Bits-1,
Data Bits-8.I am trying to get my Microcontroller Based HMI/OI to read from the PLC using SNP and SNPX Protocols.
1) I transmit the Long Break(Taking TxD Line to the SPACE State) for at least three character times.(For a default comm Baud Rate
of 19200BPS, I have held the TxD Line in the SPACE state for 50ms).
2)Next, I wait for T4 time = 100ms.
3)Then I transmit the Attach Message (for SNP) and X-Attach Message for SNPX wherein the PLC CPU ID is set to NULL as it is a Point
-to-Point Communication.
4)Next, I wait for T1 time = 10ms and then check for Attach Response(or X-Attach Response).
I am not able to elicit a response from the PLC at all.It is mentioned in the SNP Communications User's Manual and in the
Serial Communications User's Manual, that there will be no reponse from the PLC in the case of an error in an Attach Message.For
the other Messages, if there is an error, I will either get an error message or an NAK.So, if there is an error,I would like to know
what it actually is.I am including the SNP and SNPX message streams I sent for the Attach and X-Attach Messages respectively.
SNPX Attach Message: 1b 58 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 17 00 00 00 00 79
SNP Attach Message: 1b 41 00 00 00 00 00 00 00 00 30 35 30 30 30 20 20 20 17 00 00 00 42 39
I hope ypu can help me out at the earliest with regard to this and point out where exactly I am going wrong.
Thank You,
Yours Sincerely,
P.Mani.
Port 1(The Port with an RJ45 Connector).I have set the communication parameters to the default-19200BPS,Pqrity-Odd,Stop Bits-1,
Data Bits-8.I am trying to get my Microcontroller Based HMI/OI to read from the PLC using SNP and SNPX Protocols.
1) I transmit the Long Break(Taking TxD Line to the SPACE State) for at least three character times.(For a default comm Baud Rate
of 19200BPS, I have held the TxD Line in the SPACE state for 50ms).
2)Next, I wait for T4 time = 100ms.
3)Then I transmit the Attach Message (for SNP) and X-Attach Message for SNPX wherein the PLC CPU ID is set to NULL as it is a Point
-to-Point Communication.
4)Next, I wait for T1 time = 10ms and then check for Attach Response(or X-Attach Response).
I am not able to elicit a response from the PLC at all.It is mentioned in the SNP Communications User's Manual and in the
Serial Communications User's Manual, that there will be no reponse from the PLC in the case of an error in an Attach Message.For
the other Messages, if there is an error, I will either get an error message or an NAK.So, if there is an error,I would like to know
what it actually is.I am including the SNP and SNPX message streams I sent for the Attach and X-Attach Messages respectively.
SNPX Attach Message: 1b 58 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 17 00 00 00 00 79
SNP Attach Message: 1b 41 00 00 00 00 00 00 00 00 30 35 30 30 30 20 20 20 17 00 00 00 42 39
I hope ypu can help me out at the earliest with regard to this and point out where exactly I am going wrong.
Thank You,
Yours Sincerely,
P.Mani.