CTI 2572-B / 2500C-2572-B Installation and Operation Manual 17
CHAPTER 4. CAMP SERVER
4.1. Overview
The CAMP server enables client applications using Common ASCII Messaging Protocol (CAMP)) to access
controller data element types supported by the CTI 2500 Series® controllers and Siemens Series 505®
controllers. First implemented on the CTI 2572 Ethernet network module, the CAMP protocol is widely used
by HMI (Human Machine Interface) panels and SCADA (Supervisory Control and Data Acquisition) equipment
to communicate with CTI 2500 Series® controllers and Siemens Series 505® controllers. The CAMP server also
allows these controllers to be programmed via the network using PLC Workshop, programming software from
FasTrak Softworks.
The CAMP protocol includes two sub-protocols: Data Transfer and Packed Task Code. The Data Transfer sub-
protocol is an efficient means to read or write large blocks of data (up to 256 words). The Packed Task Code
sub-protocol allows up to 15 task code requests and responses to be transferred in a block of Ethernet data.
The CAMP server also supports Siemens Series 505 task codes that are sent using the NITP protocol.
4.2. Operation
The CAMP server translates the data requests contained in a CAMP or NITP message to a Special Function I/O
(SFIO) format that can be processed by the PLC. SFIO requests are placed in a queue in the order they were
received and transmitted to the PLC during the SFIO portion of the PLC scan when requested by the PLC. The
PLC will process a limited number of requests each scan. For example, the PLC will process a maximum of 8
task code requests each scan. When replies are received from the PLC, they are translated to a CAMP or NITP
message and transmitted to the client that initiated the request.
4.3. Connections
The CAMP server will support up to 24 TCP connections. In addition, it supports UDP and UDP multicast,
which are connectionless. Although the number of UDP clients that can access the CAMP server is unlimited,
an excessive number of clients can substantially increase response times. The CAMP server can be configured
to listen on one UDP multicast address.
4.4. Error Processing
If a protocol error or CAMP Data Transfer occurs, an error code is returned to the client within the CAMP
protocol. If an error occurs with a task code request (CAMP Packed Task Code or NITP request), an error code
is returned within the task code error reply. See APPENDIX A. ERROR CODES for a description of the error
codes.
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