69
9.3
Allen Bradley CSP (PCCC)
9.3.1 Overview
Ethernet-enabled Allen-Bradley legacy PLCs (such as the PLC5E, SLC-5/05, and MicroLogix series) use
a protocol called CSP (Client Server Protocol) to communicate over the Ethernet network. The flavor of
CSP used by these PLCs is also known as “PCCC” (Programmable Controller Communication
Commands) and “AB Ethernet”. The interface card supports CSP for direct connectivity to these PLCs.
Note that CSP runs under EtherNet/IP and is enabled by default when EtherNet/IP is added to the
configuration.
If a connection timeout or socket-level error occurs, the driver can be configured to perform a timeout
action as described in section 9.2.3.
9.3.2 Explicit Messaging Via Typed Read/Write Services
Register (parameter) contents are read from and written to the interface card via CSP by reference to an
integer “file/section number” and an “offset/element” within that file. Reading is performed via the CSP
“PLC5 Read” (DF1 protocol typed read, 0x68) service, and writing is performed via the CSP “PLC5
Write” (DF1 protocol typed write, 0x67) service. To read and write data, the client must reference a
“target address” and the “size of elements”. The target address is constructed according to the
conventions shown in section 9.3.3.
9.3.3 Inverter Parameter File Number Offset Format
The formula to calculate which register (parameter) is targeted in the interface card is provided in
(
)
offset
100
10
-
number
file
register
target
+
×
=
Equation 7
Refer to section 4.1 for converting parameters to register numbers. In Equation 7, “target register”
∈
[1…25444], “file number”
∈
[10…264] (which means N10…N264), and “offset” is restricted only by the
limitations of the programming software. Table 24 provides some examples of various combinations of
file/section numbers and offsets/elements which can be used to access inverter parameters. Note that
there are multiple different combinations of file/section numbers and offsets/elements that will result in
the same inverter parameter being accessed.
Table 24: CSP Target Register Examples
Parameter
Target
Register
File/Section
Number
Offset/Element
Address
Format
00.02
3
N10
3
N10:3
01.04
261
N12
61
N12:61
03.01
770
N17
70
N17:70
23.04
5893
N68
93
N68:93
In addition to providing access to the inverter parameters in their “standard” numerical locations as
mentioned above, the parameters can also be accessed in a special “assembly object” type format by
targeting integer file N50. What this means is that when N50 is targeted for reading, what is actually
returned by the interface card is the user-defined parameter data as ordered by the EtherNet/IP
produced data word configuration (refer to section 9.2.4). Similarly, when N50 is targeted for writing, the
written data is disseminated to the inverter’s parameters according to the definition contained in the
EtherNet/IP consumed data word configuration. By appropriate configuration of the EtherNet/IP
consumed and produced data word configuration, therefore, bulk access to non-contiguous but
frequently-used inverter parameters can be conveniently provided by performing only one read and/or
write instruction targeting file N50.
Because both the EtherNet/IP consumed and produced data word configurations are comprised of 32
parameter definitions, the targeted “offset/element” must be within the range of 0 to 31 inclusive. Refer
to Table 25 for some examples of N50 accesses.