1-5
1
1.5
SERIAL MODBUS INTERFACE
The 4899A and 4809A's serial Modbus interface provides RS-232 single-
ended and RS-485 (RS-422) differential signals. Signals are selected by
internal jumpers. The 4899A has a DB-25S connector on its rear panel,
the 4809A has a 26-pin flat-ribbon header and a DB-25P connector. Signal
pinouts conform to EIA RS-530 specification and are listed in Table 2-2.
The 4819A provides RS-232 single-ended signals on a DE-9S connector.
DCE/DTE jumpers let user exchange TX and RX signal pin numbers. Signal
pinouts are listed in Table 2-3.
The 4829A provides RS-422/RS-485 differential signal pairs on a DE-9S
connector. On-board jumpers let user connect the TX and RX signal pairs
together for 2-wire networks. The RX pair includes a termination network
for biasing 2-wire networks. Signal pinouts are listed in Table 2-4.
1.5.1 Modbus RTU Messages
Messages conform to the Modbus RTU format and include the device ad-
dress, command, register number, data and CRC formatted as binary bytes.
Supported Modbus commands are: 01, 02, 03, 04, 05, 06, 07, 08, and 16 for
integer values and commands 03 and 16 for floating point 32-bit values.
Integer range 16 bits or 0 to 65,536
Floating point IEEE-754
1.5.2 Baud Rates:
Parser selects closest rate to specified rate when a nonstandard rate entered.
Standard rates are: 50, 110, 300, 600, 1200, 2400, 4800, 7200, 9600, 14400,
19200, 28800, 38400, 57600, 76800 and 115200 baud.
Baud Rates: 4899A - Any rate from 50 to 115,200 baud.
4809A - Any rate from 50 to 38,400 baud.
4819A - Any rate from 50 to 57,600 baud.
4829A - Any rate from 50 to 57,600 baud.
Содержание 4809A
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