Rtu And Serial I/O Delays - GE VersaMax PLC User Manual

Configuration
For public disclosure
The VersaPro software allows configuration of RTU and Serial I/O at 115.2K baud.
However, these baud rates are not supported by the CPU. If a configuration using these
baud rates is stored to the PLC:
1. For RTU, an Unsupported Feature in Configuration fault is logged and the PLC
transitions to Stop Faulted mode.
2. For Serial I/O, the same fault is logged when the transition to Run mode occurs. The
PLC will immediately transition to Stop Faulted mode.

5.3.5 RTU and Serial I/O Delays

• The receive to transmit, turnaround, and RTS drop delay parameters can be
configured to customize communications timing for radio modems.
receive to transmit delay: The minimum length of time between the CPU
•
receiving the last character of an incoming message and the CPU asserting RTS.
Asserting RTS is followed by the transmission of the response message. This delay is
configured as a minimum time because the actual delay is dependent upon the CPU
sweep time.
• turnaround delay: The length of time between the CPU asserting RTS and the
CPU beginning to transmit a message.
RTS drop delay: The length of time between the CPU transmitting the last
•
character of a response message and the CPU dropping RTS. The RTS drop delay can
vary by ± 1 ms.
• TD is the Receive to Transmit delay
1
• TD is the Turnaround Delay
2
• TD is the RTS Drop Delay
3
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