PLC Interface Commands Introduction
PLC Interface Commands
Introduction
The EMERSON EMC T-60 Series PLC Interfaces are designed to make many of the individual intricacies of the various PLC Interfaces transparent to the user. That is to say that reading a register in a Modicon PLC uses the same procedure as reading a register in an Omron PLC. This allows a given program to be written for one PLC and then used with another PLC just by changing the PLC Interface option in your T-60 Series unit. This assumes, of course, that both PLC’s have equivalent functionality.
For example, Modicon and TI treat analog I/O very differently (Modicon treats analog I/O as simply another register, whereas TI has separate memory locations for registers and analog I/O) so they are accessed differently via the T-60 Series.
Three “calls” are the heart of the PLC communications. They are CALL
PLCINIT, CALL PLCREAD, and CALL PLCWRITE. These calls can be used in any reasonable location within a basic program running in the T-60 or
T-61 with a PLC Interface option.
This allows the use of the data in a register, bit status, analog I/O value, or any other applicable data available from a PLC in a process or interface program in the T-60 Series device.
For most of the PLC Interface Options, the PLC Interface is on COM1 of the
T-60 Series device. COM2 retains its default status. The -MOD, -PL5, and
-SL5 Options have the ability to communicate to the PLC from either COM port. In effect, this allows you to hook two PLC’s to each T-60 or T-61. In a
T-60 , COM2 is still standard RS232C. In a T-61, COM2 can still be configured to be RS232C, RS422, or RS485.
This allows the integration of a PLC and virtually any other serial communications device. For example, you can connect a PLC to COM1 and another device that uses serial communication (e.g., motion controllers, PC’s, serial displays, temperature controllers, etc.) to COM2 and communicate to all devices via the T-60 Series interface. In effect, the T-60 Series acts as an
Operator Interface and an ASCII/BASIC module in one.
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T-60 Operator's Manual
Table 3
Current PLC Interface Options
The tabel below shows the current PLC interface options.
Interface Option
-MOD
-GE9
-TI3
-TI5
-PL5
-OM1
-PL2
-SL5
-ID1
-MFX
-SQD
PLC Protocols Supported
Modbus (Modicon)
GE Series 90 (GE Fanuc)
TI305 (GE Series 1) & TI405
TI505 (Siemens/TI)
Allen Bradley PLC-5
Omron Hostlink
Allen Bradley PLC-2
Allen Bradley SLC 500
IDEC FA-1J\FA2-J
Mitsubishi FX
Square D SY/MAX
Software Version
20-0000X-02-X.XX
20-0000X-03-X.XX
20-0000X-04-X.XX
20-0000X-05-X.XX
20-0000X-06-X.XX
20-0000X-07-X.XX
20-0000X-08-X.XX
20-0000X-09-X.XX
20-0000X-10-X.XX
20-0000X-11-X.XX
20-0000X-13-X.XX+
As mentioned above, the PLC Interfaces all work in a similar, if not identical, fashion (the -PL5, -SL5, -ID1, -MFX, and -SQD interfaces are more unique than any of the others - refer to the PLC SPECIFIC sections for detailed information on how to use these interfaces).
Initialization of the PLC Interface (setting the proper communication parameters and verifying the establishment of the link between the PLC and the T-60 or T-61) always occurs with the CALL PLCINIT command. This command need only be issued once, usually during the initialization portion of your program. Any data that you wish to get from the PLC is retrieved by the CALL PLCREAD command. Data that you wish to write in a register, memory locations that you wish to define, or I/O bits you wish to set are all effected with the CALL PLCWRITE statement.
The following section describes the CALL PLCINIT, CALL PLCREAD, and
CALL PLCWRITE commands in general. Most of the PLC Interfaces developed so far use the same arguments for similar functionality, no matter which Interface is installed. Exceptions are noted in the tables. More specific information follows in sections particular to each Interface Option.
Refer to the section for your PLC to see if the “normal” implementation for a given function is different for you PLC. See the PLC and SLC specific sections on the -PL5 and -SL5 Options for the CALL PLCREAD and CALL
PLCWRITE commands for the Allen Bradley PLC-5 and SLC 500 PLC’s as they are significantly different from the rest of the interface options.
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