Design and Implementation of HC900 Control System - Allowable Function Blocks for Process and Safety Functions
Revision 1.9 HC900 Process & Safety Controller Safety Manual 37
01/14
Communications
Blocks
Peer Comm
A communications function block that allows
interconnecting controllers with Ethernet media and
networking devices to communicate with each other.
It requires one block per controller; up to 32
controllers maximum. It supports up to 8 Read and 4
Write parameters. The block does not support forcing,
but it will allow data writes to any of its inputs. Writes
into function blocks on a safety worksheet are only
permitted while operating in the “Run/Program” or
“Program” modes.
X
Peer Read
A Peer Data Exchange block that expands the Read
capability of the Peer Comm function block to 16
additional points. Multiple Peer Read blocks may be
connected to the same Peer Comm function block.
Peer Reads inside a safety worksheet are only
permitted while operating in the “RUN/Program” or
“Program” modes.
X
Peer Write
A Peer Data Exchange block that expands the Write
capability of the Peer Comm function block to 8
additional points. Multiple Peer Write blocks may be
connected to the same Peer Comm function block.
X
Modbus Slave
A communication function block that allows the
controller to act as a Master device and communicate
with slave devices using the Modbus protocol.
Requires one block per slave device, up to 32
devices maximum. Only one block may be assigned
to each device. Supports 4 read and 4 write
parameters plus provides digital indication of
communication integrity. Integer values are converted
to floating point values prior to output. If a Modbus
slave device does not respond to a request, the last
output value will be maintained. Modbus writes to a
function block inside a safety worksheet are only
permitted while operating in the “RUN/Program” or
“Program” modes.
X
Modbus Read
A communication function block that expands the
read capability of the Modbus Slave function block to
32 additional data points. Multiple blocks may be
connected to the same Modbus Slave block. The
Modbus read block has no inputs and 32 outputs. Up
to 32 registers can be configured as the source of
data for the outputs. The configuration data for each
point will consist of: the address of the source device
on the Modbus link, the register address of the
desired data, and the register type: Integer, Float, or
Bit Packed. The sixteen outputs can be connected or
tagged in the same manner as any other function
block output.
X
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