Parker Hannifin GEM6K manual Ntpoll, Network Polling Rate, Potential Error Conditions

3.Map a range of integer elements in the AB PLC to a range of integer (VARI) variables in the 6K (NTMPWI command).

4.Start polling the AB device at a specific polling interval (NTPOLL command). This updates integer data elements in the AB PLC with the data from the mapped VARI variables in the 6K.

NOTE: The VARI variables in the 6K are 32 bit values, but the integers in the AB PLC are 16 bit values. Therefore, the range for the VARI variables must be kept in the range –32767 to +32767.

Saved in Non-Volatile Memory

This command is saved in the controller’s non-volatile memory, and is remembered on power-up and RESET.

Potential Error Conditions:

•You are not allowed to map the same 6K VARI variables for read and write functions. Nor are you allowed to map the same 6K VARI variables to another PLC. If you attempt either of these conditions, the 6K will not accept the NTMPWI command and will transmit the error message “VARIABLE MAPPING CONFLICT…”.

•If you attempt to write to an AB data file of the wrong type, or to a non-existent data element, the 6K will not accept the NTMPWI command, it will transmit the error message “ERROR, INVALID FILE TYPE, NUMBER OR SIZE…” and it will automatically stop polling all mapped binary and integer variables (equivalent to executing the

NTMPRBi,i,0,i, NTMPWBi,i,0,i, NTMPRIi,i,0,i, and NTMPWIi,i,0,i, commands).

Control over Polling: If you want to stop the 6K from writing integer data to the PLC, but continue to exchange NTMPRI, NTMPRB and NTMPWB data, use the NTMPWIi,i,0,i command. If you need to stop polling all mapped variables, use the

nNTPOLL0 command.

Example:	; Identify network server #2 as an Allen-Bradley PLC at
2NTIP1,172,54,125,34
2NTCONN1	; IP address 172.54.125.34
	; Attempt connection to network server #2
2NTMPWI9,0,15,20	; File 9, elements 0-14, in the AB PLC are mapped to
2NTPOLL50	; the 6K's integer variables VARI20-VARI34
	; Start polling network server #2, set interval to 50 ms
VARI = 42	; The value of AB file 9, element 5, will be set to 42,
	; because it is mapped to VARI25

NTPOLL		Network Polling Rate
Type:	Network		Product	Rev
Syntax:	<!><n>NTPOLL<i>		6K	5.3
Units:	n = network server #
	i = polling rate (milliseconds)

Range: n = 1-6

i= 0 (disable polling) or 1-9999 (50 is recommended)

Default: 0 (disabled)

Response: 1NTPOLL: *1NTPOLL50

See Also: NTIP, NTCONN, NTMPRB, NTMPRI, NTMPWB, NTMPWI

The NTPOLL command establishes the rate at which the 6K polls the Ethernet server devices for information:

•Allen-Bradley PLC Devices: NTPOLL sets the rate at which the 6K reads and writes the VARI and VARB variables that are mapped to the Allen-Bradley PLC. Variables are mapped with the NTMPRB, NTMPRI, NTMPWB and NTMPWI commands.

•OPTO22: NTPOLL sets the rate for polling or changing the states of the input and output modules on the OPTO22. OPTO22 outputs are controlled with the \OUT and \ANO commands, and the inputs are monitored with the \IN,

\ANI, \TANI, \TANO, \TIN, \TIO, \TOUT commands.

The polling rate affects the 6K overall command execution speed (slowing the polling rate will speed up the 6K’s command processing).

page 26