Code 15 - Write Multiple Coils; Figure 2-27 Write Multiple Coils Example - Request - Siemens SIMATIC TI505 User Manual

Code 15 — Write
Multiple Coils
WARNING
!
SIMATIC TI505/TI500 MODNIM User Manual
Code 15 allows the host computer to write multiple coils. When this
command is given, successive coils are changed by an associated bit pattern
to the indicated state, where each bit indicates: 1 = ON 0 = OFF
Addressing is sequential up to the maximum memory size for a particular
secondary. The maximum number of coils that can be addressed with one
command is 800. If more are given, the whole command will be rejected with
an Exception code 03.
The broadcast address (00) can be used to change the same coils in all
networked programmable controllers.
[This command is equivalent to TIWAY Primitive 30 using data types 04, 07
(Y unpacked, packed) or data types 05, 08 (C unpacked, packed), depending
on the position of configuration Switch 10.]
Because of differences in memory mapping between Modbus PLCs
and SIMATIC TI PLCs, you should be quite certain of the effects of
the broadcast command before issuing it.
Example:
Request: 07 0F 0012 000C 02 DC08 XXXX
Figure 2-27 Write Multiple Coils Example — Request
Checksum (XXXX)
Coil status (DC08)
Number of bytes (02)
Number of coils (000C)
Start coil address (0012)
Function code 15 (0F hex)
Slave address (07)
Modbus Commands 2-33