Using modbus rtu – Watlow EZ-ZONE RUI/Gateway User Manual

Page 34

Watlow EZ-ZONE

RUI/Gateway

•

Chapter 5 Networking with a Gateway

Differences Between a User Without Password,
User With Password and Administrator
- User without a password is restricted by the

Locked Access Level [loC;l].

- A User with a password is restricted by the Read

Lockout Security [rloC] never having access to the

Lock Menu [`loC].

- An Administrator is restricted according to the Read

Lockout Security [rloC] however, the Administra-

tor has access to the Lock Menu where the Read

Lockout can be changed.

An example using Method 2 lockout may be a case

where once the RUI gateway is setup downtime due

to inadvertent and unwanted changes to the RUI

would be unacceptable. By enabling Password Secu-

rity all menus (with the exception of Unlock [UloC])

would be inaccessible until a valid password is en-

tered.
1. Press and hold the Advance and Down arrow keys

for approximately 6 seconds to enter the RUI

Page

2. Navigate to the [`LoC] Menu using the Up or

Down arrow keys.

3. Using the green Advance key navigate to the

Password Enable [pas;e] prompt and change it to

on.

4. Push the green Advance key and navigate to the

Lock Level [loC;l] prompt changing it to 1.

5. Push the green Advance key and select whether

or not rolling password [roll] should be on or

off.

6. Push the green Advance key and select a User

Password [pas;u] by using the Up or Down arrow

keys.

7. Push the green Advance key and select an Ad-

ministrator Password [pas;a] by using the Up or

Down arrow keys.

8. Push and hold the Infinity key for 3 seconds to

return to the Home Page.

Using Modbus RTU

Communications To/From a Master:

Once the gateway instance is enabled for Modbus

RTU there is one other prompt [mof] (Modbus Off-

set) that will have an impact on which parameter is

read or written to as well as which controller.

As an example, lets assume the offsets are as

shown in the graphic on the following page and the

Master wants to read instance one Closed Loop Set

Point from both Standard Bus address 1 and 4. Open

up the associated PM Users Guide and determine

whether or not the controller is configured to use Map

1 or Map 2 Modbus addresses. This can be found in

the Setup Page under the Com Menu. Once this is de-

termined, turn to the Operations Page and look in the

Loop Menu for Closed Loop Set Point. If using Map 1

you’ll notice that the Modbus register that holds the

Closed Loop Set Point value is 2160; if using Map2

then the address would be 2640. To read instance one

Closed Loop Set Point from Standard Bus address 1

the appropriate absolute Modbus address would be:

2160 + 400001 + Modbus offset (0) = 402161.

To read the closed loop set point from Standard Bus

address 4 the absolute address would be:

2160 + 400001 + Modbus offset (15000) = 417161.

When considering what the offsets will be for each

control, first determine the highest Modbus address

that you will need to access from any given control

while keeping in mind that the last available Modbus

address is 465535. Ensure the offsets for each control

do not overlap one another. As a point of reference,

the table below shows the maximum number of Mod-

bus registers in each of the EZ-ZONE controls.

With Profiles

RMC

8,500 8,000 43,400

Without Profiles

Express

ST RMC RMH RMS RML RME RMA

2,200 4,000 2,200 5,300 17,000 18,000 9,500 7,000 5,500

Note:

The Modbus Offset [M;oF] as modified through the

RUI cannot exceed 9999. Therefore, if it is desired

to utilize a Modbus offset as shown in the follow-

ing graphic (above 9999) it must be entered using

EZ-ZONE Configurator software. This software can

be downloaded free of charge from the Watlow web

site:

http://www.watlow.com/products/software/zone_config.cfm

Modbus - Using Programmable Memory Blocks

All EZ-ZONE controllers equipped with the Modbus

protocol feature a block of addresses that can be con-

figured by the user to provide direct access to a list of

40 user configured parameters. This allows the user

easy access to this customized list by reading from or

writing to a contiguous block of registers.
Note:

To use the User Programmable Memory Blocks fea-

ture, Map 2 must be selected in the controller and

the RUI. The RUI and the control must be set the

same. For the control change the mapping [map]

via the Setup Page under the [Com] Menu. For the

RUI navigate to the RUI Page and then the [Com]

To acquire a better understanding of the tables found

in the back of this manual (

See Appendix:

Modbus

Programmable Memory Blocks

) please read through

the text below which defines the column headers

used.