Schneider Electric LUFP9 Reserves relating to the RSLogix 500 example, Address Symbol Display

9. Appendix C: Practical Example (RSLogix 500)

Address	Symbol	Description
S:24	INDEX_SYS	Index register used in indexed addressing (prefix: ‘#’)
T4:1	TIMEOUT_WR_PARAM	Timer for the timeout of the parameter writing command
		(3 seconds)

The example includes a personalized screen for monitoring the data, called “CDM 2 - WR_PAR”, in order to simplify the use of this example. The content of this screen is shown below:

Address	Symbol	Display
N7:12	WR_SLAVE	Decimal
N7:13	WR_ADDRESS	Decimal
N7:14	WR_VALUE	Decimal
B3:0/2	WR_COMMAND	Binary
B3:0/3	WR_RUNNING	Binary
B3:0/4	WR_OK	Binary
N7:15	WR_INDEX	Decimal
N7:16	WRPAR_1_ADDRESS	Decimal
N7:17	WRPAR_1_VALUE	Decimal
N7:18	WRPAR_2_ADDRESS	Decimal
N7:19	WRPAR_2_VALUE	Decimal
N7:20	WRPAR_3_ADDRESS	Decimal
N7:21	WRPAR_3_VALUE	Decimal
N7:22	WRPAR_4_ADDRESS	Decimal
N7:23	WRPAR_4_VALUE	Decimal
N7:24	WRPAR_5_ADDRESS	Decimal

Address	Symbol	Display
N7:25	WRPAR_5_VALUE	Decimal
N7:26	WRPAR_6_ADDRESS	Decimal
N7:27	WRPAR_6_VALUE	Decimal
N7:28	WRPAR_7_ADDRESS	Decimal
N7:29	WRPAR_7_VALUE	Decimal
N7:30	WRPAR_8_ADDRESS	Decimal
N7:31	WRPAR_8_VALUE	Decimal
O:1.13	WRPAR_SLAVE_FCT	Hexadecimal
O:1.14	WRPAR_ADRPAR	Hexadecimal
O:1.15	WRPAR_VALUE	Hexadecimal
I:1.13	CR_WRPAR_SLAVE_FCT	Hexadecimal
I:1.14	CR_WRPAR_ADRPAR	Hexadecimal
I:1.15	CR_WRPAR_VALUE	Hexadecimal
I:1.16	TRIGGER_IN_RD_WR	Hexadecimal
O:1.16	TRIGGER_OUT_RD_WR	Hexadecimal
N7:37	————	Hexadecimal
B3:0/6	————	Binary

9.5. Reserves relating to the RSLogix 500 example

This example is perfectible. So, for instance, with an incorrect response (wrong slave number, function number, etc.), the program performs no particular processing and continues to wait for a response until it times out, even though the gateway has not re-transmitted anything because, from its point of view, the response is correct. In fact, as the whole content of the Modbus response is placed in a “Data” field, it will not be checked before being copied into the gateway’s memory. Only the frame’s Checksum is checked by the gateway.

The two “trigger bytes” located in the input word I:1.16 are not used. You should use them if it is relevant for your application to be notified each time a response related to the two personalized commands “Transactions 1” and “Transactions 2” is received by the gateway.

Compatibility with the various options offered for the “Control/Status Byte” field in “ABC” (see chapter 5 Gateway Initialization and Diagnostics, page 33) is only partially dealt with in this example. The improvements required relate mainly to managing bits 14 and 15 of the DeviceNet master’s command word and the gateway’s status word (bits 6 and 7 of the corresponding input I:1.1 and output O:1.1). Also, the use of gateway diagnostics (EC and ED fields) still needs to be defined by the user.

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