West Control Solutions N6600 - Manual (Page 40)

Read Coil Status
(Read n Bits) - 01/02
The message sent to the Controller consists of eight bytes:
The normal reply will echo the first two characters of the message received
followed by a single-byte data byte count (which will not include itself or the
CRC). For this message, there will be one byte of data per eight bits-worth of
information requested, with the least significant bit of the first data byte
transmitted depicting the state of the lowest-numbered bit required.
This function is used mostly to report controller status information; thus, a bit set to 1
indicates that the corresponding feature is currently active/enabled and a bit set
to 0 indicates that the corresponding feature is currently inactive/disabled.
If an exact multiple of eight bits is not requested, the data padding with trailing
zeros is used to preserve the eight-bit format. After the data has been transmitted,
the CRC16 value is sent.
Read Holding Registers
(Read n Words) - 03/04
The message sent to the Controller to obtain the value of one or more registers
comprises the following eight bytes:
The normal reply will echo the first two characters of the message received
followed by a single-byte data byte count (which will not include itself or the
CRC). For this message, the count value equals the number of parameter values
read multiplied by two. Following the byte count, the specified number of
parameter values are transmitted, followed by the CRC16 bytes:
Force Single Coil
(Write 1 Bit) - 05
The message received by the Controller is eight bytes long, comprising the
standard pre-amble and the address of the bit to be forced, followed by a
two-byte word whose most significant byte contains the desired truth value of the
bit expressed as 0xFF (TRUE) or 0x00 (FALSE):
Normally, this function is used to control such features as Auto-Manual Control
selection and tuning (Pre-Tune, Self-Tune). The normal reply sent by the Controller
will be a byte-for-byte echo of the message received.
Preset Single Register
(Write 1 Word) - 06
The message sent to the Controller comprises eight bytes: the address and
Function Number (as usual), the address of the parameter to be written, the
two-byte value to which the parameter is to be set and the CRC16 bytes:
The normal response from the Controller is a complete echo of the received
message.
4-4 O075-4
PM-0075