Rockwell Automation 22-SCM-232 Serial Converter Module User Manual

Page 52

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D-2

MicroLogix 1000 Example Ladder Program

Figure D.1 Example MicroLogix 1000 Ladder Logic Program

MicroLogix 1000 communications to a PowerFlex 4/40 using a 22-SCM-232

Connection:
The 22-SCM-232 connects to the front port on the MicroLogix 1000 by using a 1203-SNM Null Modem
adapter and a 1761-CBL-AP00 programming cable. The RJ45 cable on the 22-SCM-232 conencts to the
RJ45 port on the PowerFlex 4/40. The SCM provides both media (RS232 to RS485) and protocol (DF1 to
Modbus RTU) conversions.

Additional PF4/40 drives can be added. Use one AK-U0-RJ45-SC1 Splitter Cable for connecting to the
first drive, and one AK-U0-RJ45-TB2P for every drive. The "Local Node Address" in the MSG instruction
indentifies the drive node to communicate with.

PF4 Parameters: 22-SCM-232 parameters:
36 [Start Source] = 5 (Comm Port) 1[Adapter Cfg] = RTU Master
38 [Speed Reference] = 5 (Comm Port) 2[DF1 Addr Cfg] = 1 (this MUST equal Parameter 104 of the PF
4/40 it is connected to)
103 [Comm Data Rate] = 4 (19.2K) 3 [DF1 Rate Cfg] = 19.2k bps
104 [Comm Node Addr] = 1
107 [Comm Format] = 0 (RTU 8-N-1)

For the PowerFlex 4/40 drives, 19.2K and 8-N-1 are a requirement and can not be changed. The data rate
of the controller and SCM MUST be equal to each other, but can be set faster or slower than the drives
baud rate if desired. It is recommended that 19.2K be used for ALL serial connections (controller, SCM,
and drives) to be consistent and to avoid any errors.

This rung clears the read data area (N7:10-19) on the first program scan (N7:0 = a constant 0) and starts the
messaging process by clearing the EN bit of the first MSG instruction.

0000

S:1

15

First Pass

U

N7:50

15

Enable
(EN)

COP

Copy File
Source

#N7:0

Dest

#N7:10

Length

10

COP

Logic Status

This rung sets the timeout value for the first MSG instruction.

0001

N7:50

15

Enable
(EN)

N7:50

12

Error
(ER)

N7:50

13

Done
(DN)

EN

DN

TON

Timer On Delay
Timer

T4:0

Time Base

0.01

Preset

200<

Accum

0<

TON

MSG #1
Time Out
Timer

T4:0

DN

MSG #1
Time Out
Timer

L

N7:50

8

Time Out
(TO)

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