Omron SYSMAC CV1000 User Manual

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4-3-5 Frame Checksum (FCS) Calculation
The frame checksum is an 8-bit value converted into two ASCII characters. The
8-bit value is the result of an EXCLUSIVE OR sequentially performed between
each character in a transmission, from the first character in the frame to the last
character of the text in that frame.
@ 10 RR 0000001 42 * CR
@ 0100 0000
XOR
1 0011 0001
XOR
0 0011 0000
XOR
R 0101 0010
1 0011 0001
Result 0100 0010
↓↓
42
Example
Converted to hexadecimal
and treated as ASCII
Node
No.
Header Text FCS Termi-
nator
FCS Calculation Program The following program is an example of how frame checksum calculations can
be performed on received data.
400 ∗FCSCHECK
405 L=LEN(RESPONSE$) Transmit/receive data. . . . . . . . . . . . . . . . . . . . .
410 Q=0:FCSCK$=” ”
415 A$=RIGHTS$(RESPONSE$, 1)
417 PRINT RESPONSE$, A$, L
420 IF A$=”∗” THEN LENGS=LEN(RESPONSE$)–3 ELSE LENGS=LEN(RESPONSE$)–2
430 FCSP$=MID$(RESPONSE$, LENGS+1, 2) Receive FCS data
440 FOR I=1 TO LENGS Number of characters in FCS calculation range.. . . . . . . . . . . . . . . . . . . . .
450 Q=ASC(MID$(RESPONSE$, I, 1)) XOR Q
460 NEXT I
470 FCSD$=HEX$(Q) FCS calculation result. . . . . . . . . . . . . . . . . . . . . . . . .
480 IF LEN(FCSD$)=1 THEN FCSD$=”0”+FCSD$
490 IF FCSD$<>FCSP$ THEN FCSCK$=”ERR”
495 PRINT ”FCSD$=”;FCSD$, ”FCSP$=”;FCSP$, ”FCSCK$=”;FCSCK$
500 RETURN
Note 1. Received data contains an FCS, delimiter/terminator, etc. If the data is not
received normally, however, any of these parts may be missing or corrupted.
Be sure to allow for the possibility of missing or corrupted data when receiv-
ing data at the host.
2. In this example, the code for CR (CHR$ (13)) is not included in RE-
SPONSE$. Modify lines 415 and 420 to include the code for CR.
C-mode Commands Section 4-3

Omron SYSMAC CV1000 Specifications

General

Manufacturer	Omron
Type	PLC
Memory Capacity	Not specified in detail
Communication Ports	RS-232C
Power Supply	24 VDC or 100-240 VAC (depending on model)
Operating Temperature	0°C to 55°C
Humidity	10% to 90% (non-condensing)
Vibration Resistance	10 to 57 Hz, 0.075 mm amplitude
Shock Resistance	10 G
Model	SYSMAC CV1000

Summary

SECTION 1 Introduction

1-3 Communications Specifications

SECTION 2 Switch Settings and Communications Parameters

2-1 CPU Settings and Parameters

2-2 Host Link Unit Settings and Parameters

Details on Host Link Unit components, switches, and setting procedures.

SECTION 3 Installation

3-3 Connection Cables for the Host Link Unit

3-4 RS-232C Connections

Specifications and connection methods for RS-232C connections.

3-5 RS-422 Connections

Specifications and connection methods for RS-422 connections.

3-9 Wiring

SECTION 4 Communications

4-1 Initial Communications Test

Steps for performing an initial test to verify system operability.

4-3 C-mode Commands

Details C-mode commands, protocol, blocks, and checksum calculation.

4-5 Communications Timing

Explains transmission timing in full-duplex and half-duplex communications.

SECTION 5 C-mode Commands

5-1 C-mode Command List

5-22 STATUS READ

5-24 ERROR READ

Reads and clears PC errors.

SECTION 6 Maintenance and Troubleshooting

6-1 Maintenance

Explains maintenance methods and procedures for the Host Link System.

6-2 Indicators

6-3 C-mode Response Codes

Appendix D Sample Programs Including Commands for Host Computer

Program Example 1: Data Transfer to Host Computer (SEND)