Appendix B
Modbus Firmware
With the release of EasySet V1.2.3, SNAP Link adapters can load a new version of script firmware to increase the
reliability of wireless transmissions, by allowing an automatic number of retransmissions by the Master adapter.
This multicast retry feature ensures the master continues to retransmit a command if no response is received
due to the original transmission. By adjusting two parameters, you can balance the number of retries attempted
by the Master adapter. However, lag or latency is introduced by each retry.
Select Modbus script, as shown, for uploading the Modbus firmware to the
connected SNAP Link adapter.
The Modbus tab enables retransmission by the Master adapter based on retry
count and the waiting period between them.
Delay between retries.
The delay between retries is a millisecond timer that counts down after the
Master adapter transmits a modbus command. Once the transmission occurs,
the Master adapter will count down the assign number, in milliseconds. If a reply
is not received before the timer reaches zero, the Master unit will retransmit the
original Modbus command up to the number of Retry count assigned
Retry count
The number of times the Master will re
-transmit the
original broadcast if no response is received within the
Delay between retries setting.
Note:
Your Modbus application may be affected by lag due to these settings. If a Master adapter has to
retry to the maximum number set, it will incur a lag in milliseconds equal to the following formula:
“Delay between retries” * “Retry Count” = “Maximum milliseconds of lag potentially added after each
Modbus command is transmitted.
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SNAP Link
Summary of Contents for SNAP Link
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