McQuay Micro Tech Open Protocol Driver Manual | Page 35 of 35 |
Appendix C. Troubleshooting
Appendix C.1. Connection Problems
The driver produces a timeout each time a message is sent. If the number of timeouts is the same as the number of messages sent then you know that the McQuay device has never sent a response. The following reasons may be applicable:
•Incorrect connection settings - the messages sent by the FieldServer cannot be interpreted by the McQuay device.
•Incorrect connection wiring – the McQuay device may require a jumper on its serial port to deflect hardware handshaking. Refer to the vendor manual.
•Serial port failure – If the Tx LED is not flashing each time a message is sent, the port is not working
•The McQuay device is off.
•If the Node_ID and Route are incorrect, the McQuay device will not respond at all.
Appendix C.2. Negative Acknowledgement - NAK
The Server sends a NAK message and increments the NAK stat each time a poll is unsuccessful. An occasional NAK may indicate a corrupted message. If the number of NAK's is the same as the number of transmitted messages to a Node, however, one of the following problems could apply:
•Bad Password - the password specified in the "read" command did not match any of the access level passwords stored in the MicroTech controller to which the terminal is connected. Call FST Tech support for default passwords or call your Vendor. FST recommends checking the password first as in almost all reports the problem was resolved by changing the password.
•Device has been polled with an invalid command code.
•Bad Node_ID / Route parameters for the node.
•The MCQ device received the message and thought it was badly formatted. This is unlikely on a repeated basis unless the connection settings were slightly wrong.
•The packet structure was invalid
•The packet was received with a parity or framing error
Appendix C.3. Node ID problems
If the Node is incorrectly specified, the FieldServer will not get a response from the McQuay unit. The ID used to communicate with the McQuay unit needs to be determined. This may not be the same as shown on the Rotary switches of the unit. Note that McQuay uses Hexadecimal notation for addressing, therefore, if connection to the Unit is with address 0201, this is in Hex and the Node ID for the FieldServer configuration needs to be 513.
Appendix C.4. Server Side Configuration – Consecutive Addresses
Some variables have their values stored in two consecutive address locations. When the Client polls for the value it actually sends two read messages – one for each address. When configuring the Server side, therefore, it is necessary to define two Map Descriptors for variables which require two consecutive addresses.
Map_Descriptors |
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Map_Descriptor_Name | ,Data_Array_Name | ,Data_Array_Offset | ,Function | ,Node_Name | ,Address | ,Length |
Supply Fan Status | ,DA_AI_01 | ,01 | ,Passive | ,Node_A | ,1118 | ,1 |
Supply Temp | ,DA_AI_01 | ,02 | ,Passive | ,Node_A | ,1063 | ,1 |
Space Temp | ,DA_AI_01 | ,03 | ,Passive | ,Node_A | ,1066 | ,1 |
Control Temp Part 1 | ,DA_AI_01 | ,04 | ,Passive | ,Node_A | ,1074 | ,1 |
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