102
CMC TECHNICAL REFERENCE MANUAL
1X36003 Version 2.52
1996-1999 Ingersoll-Rand Company
Date of Issue: 18-Oct-1999
(CMC Base Control Modules). Refer to the table for the Coil list for the MODBUS Absolute
Addresses supported by the CMC-MODBUS Interface.
NOTE
This function will override the CMC’s current state. The forced state will remain valid
until the CMC next solves the coil. The coil will remain forced if it is not programmed in
the controller's logic.
CAUTION
The position of the REMOTE COMMUNICATIONS DISABLED/ENABLED
selector switch is NOT considered when forcing coils or writing registers to the CMC.
Reads and Writes are always enabled. Repeatedly writing a value to a register or
forcing a coil without regard to the position of the switch can effectively disable a local
write. Please use caution when writing registers or forcing coils.
Example: Forcing Multiple Coils
To force a reset (absolute address 00222, relative address DD) and start (absolute address
00225, relative address E0) of the compressor the following command is sent...
The number of contiguous coils is four (00225, 00224, 00223 and 00222). The number of
data bytes is one because we can set up to eight coils in a single byte. The coil data is nine
because we want to set the first bit and fourth bit in the byte (0000-1001, the bytes are
numbered right to left). All bits not used are padded with zero.
The response from this command is similar to the command sent except that the number of
data bytes and the coil data themselves are not echoed:
Function 16 (10 Hex) - Preset Multiple Registers
Presets values into a sequence of contiguous holding registers (MODBUS 4x references).
When broadcast, the function presets the same register references in all attached slaves
Device
Functio
n
Address
Number of
Coils
Numbe
r
of Data
Coil
Data
CRC
Address
Code
Hi
Lo
Hi
Lo
Bytes
Lo
Lo
Hi
01
0F
00
DD
00
04
01
09
12
83
Number of
Device
Functio
n
Address
Coils
CRC
Address
Code
Hi
Lo
Hi
Lo
Lo
Hi
01
0F
00
DD
00
04
C4
32
