16: Performing Commands - GE 239 Instruction Manual

7 COMMUNICATIONS
Some PLCs may not support execution of commands using function code 5 but do support storing
multiple setpoints using function code 16. To perform this operation using function code 16 (10H), a
certain sequence of commands must be written at the same time to the 239. The sequence consists
of: Command Function register, Command operation register and Command Data (if required). The
Command Function register must be written with the value of 5 indicating an execute operation is
requested. The Command Operation register must then be written with a valid command operation
number from the list of commands shown in the memory map. The Command Data registers must be
written with valid data if the command operation requires data. The selected command will execute
immediately upon receipt of a valid transmission.
a) MESSAGE FORMAT AND EXAMPLE
Master Transmission
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
BYTE COUNT
DATA 1
DATA 2
CRC
Slave Response
SLAVE ADDRESS
FUNCTION CODE
7
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
CRC
7-10
Courtesy of NationalSwitchgear.com
Bytes Example (hex)
- 1 byte 11
- 1 byte 10
- 2 bytes 00
80
- 2 bytes 00
02
- 1 byte 04
- 2 bytes 00
05
- 2 bytes 00
01
- 2 bytes 7E
CE
- 1 byte 11
- 1 byte 10
- 2 bytes 00
80
- 2 bytes 00
02
- 2 bytes 42
B0
239 Motor Protection Relay
7 COMMUNICATIONS

7.14 16: PERFORMING COMMANDS

message for slave 11
store Setpoints
Setpoint address 0080
2 Setpoints (4 bytes total)
4 bytes of data
data for address 0080
data for address 0081
CRC calculated by the master
message from slave 11
store Setpoints
Setpoint address 0080
2 Setpoints
CRC calculated by slave
GE Multilin