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ModbusTCP VIM v3.10.51 Release Notes
By Nobin William
Product: IOD-4101 - Modbus TCP/IP Master Driver (General Modbus TCP/IP Communications)

The following release notes are for the ModbusTCP VIM firmware v3.10.51.

Product Description:

These release notes are for the ModbusTCP VIM firmware v3.10.51. The previous released firmware version is v3.10.37. The flash procedure is documented in the product manual. This version of the firmware is identical to the released firmware v3.10.37, with functionality enhancements and corrected defects as noted below.

Who should upgrade?

Recommended for all Modbus TCP applications.

What's New in this Release?

The following defects were corrected:

1. The use of an asynchronous ICMP ping to determine device availability caused a network memoryleak. This resulted in the VIM to lose the network. This defect has been corrected by changing the ping to synchronous.

2. Added a sequence # and device IP to the ICMP ping requests. This ensures the response is associated with the proper device handler task. Previously, the ping response was incorrectly routed to a different device handler task. In addition, invalid ICMP echo responses are now being discarded.

3. Added extra checking of response messages received from bridge/gateway devices using RTU Via TCP messaging. This prevents incorrect routing of responses to the wrong device handler task, eliminating co-mingling of responses from multiple sub-devices.

4. Added CRC checking for error responses when using RTU Via TCP messaging.

The following enhancements were implemented:

1. Added a new Special Data2 flag, value 0x8000 to discard output requests following a VIM switchover. This flag applies to Output only datasets. After a VIM switchover, output data is sent to the field devices by default. This flag prevents this from happening and is used primarily for serial devices which are communicating via a bridge/gateway.

2. Added a new Special Data2 flag, value 0x1000 to discard output requests following reconnection with devices after a total network loss. Further, after network loss the output dataset status remains good to allow DeltaV Control Modules to continue their normal functionality. This flag applies to Output only datasets, and is available only when using RTU via TCP messaging.

3. Modified device reconnect algorithm so that on loss of connection to primary socket, the VIM immediately attempts to reconnect using secondary socket, or vice versa. Previous default was to attempt reconnect after 15 seconds.

4. Added ICMP ping to determine if a Bridge/Gateway device was present after a request/response failure with a sub-device. This prevents the TCP connection from termination if a single sub-device fails to respond.

5. Added ICMP ping to determine if the Primary IP was present when communicating with the Secondary IP. This allows the VIM to do fast switchover back to Primary IP when the Secondary connection is lost.

6. Added a new Special Data2 flag, value 0x800 for bridge device connections where there are more than one sub-devices under a bridge. With this flag, when one sub-device fails, the VIM will immediately perform a switchover. Default functionality is to wait for all sub-devices to fail before the connection is closed.

7. Modified the RTU via TCP scan algorithm. During the input dataset scan, if any output pending is detected, the input scan is suspended and all output datasets are handled as a priority. The input scan then resumes after output handling is complete.

Please contact us for any questions about these release notes at:

MYNAH Technologies
390 South Woods Mill Road, Suite 100
Chesterfield, MO 63017