Allen-Bradley MicroLogix 1400 User Manual

Publication 1766-RM001A-EN-P - October 2008
Communications Instructions 397
Communication Status Bits
The following communication status bits allow you to customize or
monitor communications servicing. See General Channel Status Block on
page 64 for additional status information.
Application Example
The SVC instruction is used when you want to execute a communication
function, such as transmitting a message, prior to the normal service
communication portion of the operating scan.
You can place this rung after a message write instruction. CS0:4/MCP is
set when the message instruction is enabled and put in the
communications queue. When CS0:4/MCP is set (1), the SVC instruction is
evaluated as true and the program scan is interrupted to execute the
service communication’s portion of the operating scan. The scan then
resumes at the instruction following the SVC instruction.
Controller Channel Select Setting Channel(s) Serviced
MicroLogix 1400 1h Channel 0
2h Channel 1
4h Channel 2
7h All Channels
Communication Status Bits
Address Description
Channel 0 Channel 1
CS0:4/0 ES:4/0 ICP - Incoming Command Pending
CS0:4/1 ES:4/1 MRP - Incoming Message Reply Pending
CS0:4/2 ES:4/2 MCP - Outgoing Message Command Pending
CS0:4/4 CAB - Communications Active Bit
0000
CS0:4
MCP
SVC
Service Communications
Channel Select 0001h
SVC
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Allen-Bradley MicroLogix 1400 Specifications

General

Processor	32-bit
Expansion Modules	Up to 7 expansion I/O modules
Power Supply	24V DC or 120/240V AC
Programming Software	RSLogix 500
Communication Ports	Ethernet, RS-232/RS-485 combo port
Controller Type	Programmable Logic Controller (PLC)
Series	MicroLogix
Digital Outputs	12
Analog Inputs	6 (embedded)
Analog Outputs	2 (embedded)
High-Speed Counter	6 high-speed counters
Pulse Output	2 (embedded)
Ethernet Port	Yes