Publication 1763-RM001C-EN-P - October 2009
Protocol Configuration
527
Modbus RTU Master Communications Configuration Parameters
Parameter
Options
Programming
Software Default
Channel
Channel 0
0
Driver
Modbus RTU Master
Baud Rate
300, 600, 1200, 2400, 4800, 9600, 19.2K, 38.4K
19.2K
Parity
none, even, odd
none
Control Line
No Handshaking, Full-Duplex Modem (RTS on), Half-Duplex Modem (RTS/CTS handshaking),
No Handshaking (485 Network)
No Handshaking
Inter-character
Timeout (x1 ms)
0 to 65535 (can be set in 1 ms increments); 0 = 3.5 character times
Specifies the minimum delay between characters that indicates the end of a message packet.
0
RTS Off Delay
(x20 ms)
0 to 65535 (can be set in 20 ms increments)
Specifies the delay time between when the last serial character is sent to the modem and
when RTS is deactivated. Gives the modem extra time to transmit the last character of a
packet.
0
RTS Send Delay
(x20 ms)
0 to 65535 (can be set in 20 ms increments)
Specifies the time delay between setting RTS until checking for the CTS response. For use
with modems that are not ready to respond with CTS immediately upon receipt of RTS.
0
Pre Transmit Delay
(x1 ms)
0 to 65535 (can be set in 1 ms increments)
When the Control Line is set to
No Handshaking
, this is the delay time before transmission.
Required for 1761-NET-AIC physical Half-Duplex networks. The 1761-NET-AIC needs 2 ms of
delay time to change from receive to transmit mode.
When the Control Line is set to
Half-Duplex Modem or Full-Duplex Modem
, this is the
minimum time delay between receiving the last character of a packet and the RTS assertion.
0
Stop Bits
(1)
(1) MicroLogix 1100 OS Series B FRN 4 or later
1,5,2
1
Data Bits
(1)
7
8
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