Loopback Test; Store Multiple Setpoints - GE 469 Communications Manual

MODBUS FUNCTIONS

Loopback Test

Store Multiple Setpoints

10
MESSAGE FORMAT AND EXAMPLE:
Request status from slave 11.
Master Transmission
Slave Address
Function Code
CRC (low, high)
Slave Response
Slave Address
Function Code
Device Status
CRC (low, high)
Modbus Implementation: Loopback Test
469 Implementation: Loopback Test
This function is used to test the integrity of the communication link. The 469 will echo the
request.
MESSAGE FORMAT AND EXAMPLE:
Loopback test from slave 11.
Master Transmission
Slave Address
Function Code
Diagnostic Code
Data
CRC (low, high)
Slave Response
Slave Address
Function Code
Diagnostic Code
Data
CRC (low, high)
Modbus Implementation: Preset Multiple Registers
469 Implementation: Store Multiple Setpoints
This function code allows multiple setpoints to be stored into the 469 memory. Modbus
"registers" are 16-bit (two byte) values transmitted high order byte first. Thus all 469
setpoints are sent as two byte values. The maximum number of setpoints that can be
stored in one transmission is dependent on the slave device. Modbus allows up to a
maximum of 60 holding registers to be stored. The 469 response to this function code is to
echo the slave address, function code, starting address, the number of Setpoints stored,
and the CRC.
Bytes Example
1 0B message for slave 11
1 07 read device status
2 47 42 computed CRC error code
Bytes Example
1 0B message from slave 11
1 07 read device status
1 59 status = 01011001b
2 C2 08 computed CRC error code
Bytes Example
1 0B message for slave 11
1 08 loopback test
2 00 00 must be 00 00
2 00 00 must be 00 00
2 E0 A1 computed CRC error code
Bytes Example
1 0B message from slave 11
1 08 loopback test
2 00 00 must be 00 00
2 00 00 must be 00 00
2 E0 A1 computed CRC error code
469 MOTOR MANAGEMENT RELAY – COMMUNICATIONS GUIDE
COMMUNICATIONS GUIDE
Description
Description
Description
Description