Configuring Parameters through the Configuration Group Registers

Overview

This topic describes configuring a Momentum 170ENT11001 using the Modbus TCP/IP protocol.

Configuration Group Registers

WARNING

LOSS OF COMMUNICATION — INDEFINITE HOLDUP TIME

Configure the controller to periodically read the I/O module health (word 10) of the system status block, register 4F801 hex, of the Momentum 170ENT11001 to verify that the communication between the controller and the Momentum 170ENT11001 is operational and that the controller is healthy.
The system status block is described in the System Status Block Table in the Using the Status Group Registers.

If indefinite Holdup Time is selected, and communication is lost between the controller and the Momentum 170ENT11001, the I/O outputs will hold last value written until communication is reestablished.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

The configuration group contains four registers that are used by the adapter:

outputs holdup timeout value register
ownership of write privilege register
reservation time register
configuration save/get current IP address register

A block of registers in this area is reserved for use by distributed I/O.

Outputs Holdup Timeout Value
Web page that accesses register	Register as seen through Modbus TCP/IP
Configure Communication Adapter Parameters page	4F001 hex
Reference 4F001 specifies the amount of time that outputs will be held in their current state if they are not updated by a new Modbus TCP/IP Write. If the module’s holdup time expires before a new Modbus TCP/IP Write is received, all outputs on modules that do not have parameters are set to logical 0 (zero). Modules that have their own parameter settings will go to their configured state. The field length is one word. The timeout value is expressed in units of 10 milliseconds. Valid values are either 0 (zero) or a range of 30 (300 milliseconds) through 6000 (60 seconds). The default value is 100 (1 second).
Note: The value of 0 (zero) in this register indicates an indefinite holdup time, and the outputs will not change if they are not updated by a Modbus TCP/IP write.
The register’s contents can be read using a Modbus TCP/IP read.
You can store this parameter in FLASH. Reference Configuration Save.

Registers follow a logical order, but here the ownership of write privilege register discussion is presented before the reservation time discussion because understanding ownership of write privileges helps to understand the function of reservation time.

Ownership of Write Privilege
Web page that accesses register	Register as seen through Modbus TCP/IP
Configure Communication Adapter Parameters page	4F401
Once the adapter’s reservation timer has expired, it will give sole write privilege to the first node that writes to the adapter using the Modbus TCP/IP write. The adapter maintains an internal timer for handling the write privilege. The timer will reserve sole privilege to that node as long as the node continues to write to the adapter within the reservation time.
The ownership register is used so that more than one Modbus device can have write access to the Ethernet communication adapter. Up to three remote devices can have write access at the same time. This special case overrides the reservation time limit. The ownership register is six words starting at location 4F401, two words for the IP address of each device. The default setting for each ownership register is null (no owner). Register 4F401 contains the first owner's IP address, register 4F403 the second owner's IP address, and 4F405 contains the third owners IP address. All three owners have the same write privileges. The ownership registers can be stored in the non-volatile or FLASH. With those addresses stored, any of those three nodes may then write to the adapter in addition to the original privileged node. This allows up to four nodes to concurrently own write privilege to the adapter.
Two types of times: Note that this reservation time is separate from the outputs holdup time and applies only to the write privilege.
Any node may read the input data or status information from the adapter.
You can store this parameter in FLASH. Reference Configuration Save.

Reservation Time
Web page that accesses register	Register as seen through Modbus TCP/IP
Configure Communication Adapter Parameters page	4F002
The Ethernet communication adapter is dedicated to one Ethernet device. Reservation timeout is: amount of time (default = 60 seconds) that the output module will be dedicated to an Ethernet device that is no longer communicating with that adapter The range is 30 (300 milliseconds) through 6000 (60 seconds). If the timeout expires, this unit will be dedicated to the next device that writes to the adapter.
You can store this parameter in FLASH. Reference Configuration Save.

Configuration Save/Get Current IP Address
Web page that accesses register	Register as seen through Modbus TCP/IP
Configure Communication Adapter Parameters page and Configure IP Parameters page	4F411 hex
Modbus TCP/IP Write: Configuration Save
This reference serves a dual purpose, depending on whether the application issues a Modbus TCP/IP write or a Modbus TCP/IP read. When the register issues a Modbus TCP/IP write the register name is configuration save, and when the register issues a Modbus TCP/IP read the register name is get current IP address.
For a Modbus TCP/IP Write the reference is treated as a one-word register, with the application writing one word of data. The Modbus TCP/IP Write data may consist of a value from 0 (zero) to 15, a bit-masked OR (the Boolean logical OR).
If a data 1 (one) is written to the reference, the adapter will save its currently assigned IP address to FLASH. If a new initialization occurs and the adapter cannot find a BOOTP server, the adapter will use this saved address.

The configuration register values for the 4F411 hex register: Modbus TCP/IP write only.

Register	Register Decimal Value	Register Binary Value	Action
4F411 hex	0	0000	Clears the configuration in FLASH: Cleared are the configured IP parameters, the three (3) master IP addresses, the outputs holdup timeout value, and the reservation time values.
	1	0001	Saves the configured IP to FLASH
	2	0010	Saves the three (3) Master IPs addresses to FLASH
	4	0100	Saves the Outputs Holdup Timeout Value to FLASH
	8	1000	Saves the Reservation Time to FLASH

Example: If you want to save reservation time, outputs holdup timeout value, and save the configured IP to FLASH:

Add the register decimal values:

1 + 4 + 8 = 13
Enter the decimal value 13 into the register.
The value displays in binary:

00001101

Configuration Save/Get Current IP Address
Web page that accesses register	Register as seen through Modbus TCP/IP
Configure IP Parameters page	4F411 hex
Modbus TCP/IP Read: Get Current IP Address
This reference serves a dual purpose, depending on whether the application issues a Modbus TCP/IP write or a Modbus TCP/IP read. When the register issues a Modbus TCP/IP write, the register name is configuration save, and when the register issues a Modbus TCP/IP read, the register name is get current IP address.
For a Modbus TCP/IP read the reference is treated as a two-word register, with the application reading two words of data. If the adapter has IP parameters saved in its non-volatile, FLASH, it will return its current IP address to the Modbus TCP/IP read, indicating that it has stored parameters. If IP parameters are not currently saved, the adapter returns all ones (FFFFFFFF hex) to the read.